General aviation pilot reported an airborne conflict during departure from non-towered airport 79C with a jet that was descending into nearby ATW airport. Reporter stated the proximity of the two airports and their traffic patterns pose a systemic safety issue.

Narrative

I was on a personal VFR flight leaving ZZZ at about XA:43. Although I hadn't flown in about 2 months; I was healthy; well rested; not in a hurry; and not under any particular stress. The weather included some gusty surface winds but was otherwise good VFR.After departure from Runway XX; Aircraft Z reported 15 NM east inbound. I saw it on my ADS-B; so I turned to a heading of 090 to allow him to pass to my north; we had a pleasant radio exchange in which we each acknowledged seeing and avoiding the other; and he passed well to the north of me as he was eastbound into ZZZ. I mention this to illustrate that I was monitoring radio and ADS-B traffic; and was not in a hurry. Likewise; after my return to ZZZ; I wanted to do 2 more takeoffs and landings; and held short of Runway XX for an extended period of time out of courtesy to Aircraft A who announced he was inbound shooting a practice IFR approach; that pilot also thanked me for my patience.I had intended to fly just locally but after clearing the Aircraft Z traffic I decided to fly to 79C; Brennand Field; an untowered airport just south of ATW's Class Delta airspace. I turned northwest; gave position announcements to FLD traffic on their CTAF; then turned north along the western shore of Lake Winnebago at 3000 feet MSL; and communicated with OSH Tower to transition through their Class D airspace. About 2 NM north-northeast of OSH; I saw traffic on my ADS-B/EFB tablet display; and then quickly acquired that traffic visually - Aircraft Y at about 2 o'clock and 2 NM from me; flying from east to west in front of me and above my altitude but descending out of the approximately 3000 feet broken cloud deck. OSH Tower hadn't mentioned it to me.I turned slightly east to assure separation behind the jet; then resumed inbound to 79C once safely behind the jet. Then; on the north edge of OSH's airspace; I requested a frequency change so that I could monitor 122.9; the CTAF at 79C.Surface wind was out of the north-northeast at about 15G20. I began a descent; and announced on 122.9 my intention to execute a low pass over Runway 36 at 79C; then make a left turn to depart the area southwest-bound. I have landed at 79C multiple times in the past; and am aware that ATW's Class D begins only 2 NM to the north of 79C.There was no other traffic on the radio 122.9 at 79C; and I scanned carefully for NORDO traffic. Seeing none; I performed my low pass over Runway 36 at about 50 - 100 feet AGL; then immediately began my left-turning climb. At that point; as I was turning through a heading of about 300; my ADS-B/EFB indicated traffic 0.25 NM away and 1000 feet above; I looked up and saw a jet; presumably the same one I had seen earlier; passing left-to-right above and in front of me; presumably descending into Runway 03 at ATW. I continued my turn to the left as the jet passed off to my right; still above me; and there was no further conflict. I remained well clear of ATW's Class D the entire time.Assessment: While we were not 'dangerously close;' the potential was there; and in any case it was too close for my personal taste. Still; I may have inadvertently caused the Aircraft Y pilot and/or the ATW Controller some heartburn; which I regret; and which; in retrospect; I could have avoided.Nonetheless; there is a structural issue here too: the extended centerline of Runway 03 at ATW passes only 1 NM northwest of 79C; and 79C uses left traffic. So any aircraft taking off from Runway 36 at 79C; or executing a go-around; or; as in my case; a low pass; will be likely executing a left turnout; and thus putting themselves in potential conflict with traffic on an extended straight-in final to Runway 03 at ATW. And a higher-performance aircraft than mine leaving 79C will be climbing more quickly; and possibly turning less tightly; both of which would further eat into or erase completely the separation margins that I experienced.I'm really not sure how to 100% prevent this situation. Personally; I could/should have paid more attention to where Aircraft Y was after giving way to it just north of OSH. Perhaps I also could have alerted ATW Tower of my intentions; although 79C is not in their airspace. Or I could have at least monitored ATW Tower frequency on my COM2 radio.However; these personal actions; helpful though they may be; won't address the systemic issues here. Most planes departing 79C will be monitoring only 122.9; if they have a radio at all; and they will be making standard left traffic/left turnouts. But if the winds favor 36 at 79C; they will more than likely also favor 03 at ATW; so the potential for conflict will remain.I thought perhaps changing 79C to be right-hand traffic for 36 might be a helpful option; but; on closer inspection; unfortunately there's a pair of towers just south-southeast of the field that would be a hazard if people were trying to fly a right downwind to right base for 36.What else might help? I don't know if the Tower personnel at ATW routinely monitor 79C's CTAF 122.9; but if they don't; perhaps they should. Even better; if they see someone inbound to 36 at 79C simultaneous with an inbound to 03 at ATW; perhaps they could transmit on both 122.9 and their Tower frequency of 119.6; alerting both aircraft to what they see. This won't help when the Tower is closed; typically at night; or if the 79C traffic is NORDO; but it would probably help 80 - 90% of the time.Also; it might be good to have a permanent NOTAM for both fields; indicating that when Runway 03 is in use at ATW; there is potential for conflicts between traffic arriving at ATW and traffic departing 79C with a left turnout from Runway 36.As for me; I will certainly be more vigilant for this particular conflict when I'm operating in or out of 79C in the future.