Pilot reported inadvertently entering the class D airspace surrounding Fallon Naval Air Station while executing the published missed procedure on the FLX VOR-B approach.

Narrative

I live in a rural area and rarely fly in controlled airspace. I flew to the Fallon area to practice approaches for an upcoming check ride. On the flight to the Hazen VOR I was in contact with Oakland Center and advised them of my request to fly a practice VOR-B approach into Fallon Municipal Airport. They said fine and advised me to squawk VFR and to change to advisories frequency. I assumed that I did not need to contact ATC to practice this procedure. I flew the approach and at the missed approach point flew the published missed procedure. Unbeknownst to me this published missed procedure took me into the Fallon Naval Air Station Airspace; which is only 1 mile from Fallon Municipal Airport. I did not know that I flew into their airspace until on a subsequent flight; the Approach Controller contacted me and asked me to call base operations upon landing. I made this call and was told to expect a call from one of the offices.I think the ambiguous instruction I received from Oakland Center along with the close proximity of the Fallon Naval Air Station Class D airspace to Fallon Municipal Airport contributed to this situation. I think that the airspace around Fallon Municipal should be enlarged to provide operations so as not to infringe upon the Fallon NAS airspace.