Light aircraft pilot reported loss of directional control after landing that resulted in a runway excursion.

Narrative

Landing runway 290 at Sonoma Skypark 0Q9. CAVU with wind reported 210 at 8 from APC ASOS. Wind T vector at airport indicating gusty and variable between 200-230.Made normal visual approach to the runway and touched down in 3 point attitude. The aircraft bounced. I added power to stabilize then removed to settle back to runway. My ailerons were fully deflected into the wind. The aircraft left the runway to the left and entered the grass overrun. Concerned about a ground loop I added power which straightened the plane and then removed power. Plane settled to the grass and I began to move back to the runway (which is 40 feet wide) and the plane struck a ditch which is perpendicular to the runway not visible because of tall grass and weeds. Plane came to a stop shortly past the ditch.I believe the landing would have ended normally if not for the hidden ditch. I should have been slower on initial touch down by holding the aircraft off of the runway until it settled at a slower ground speed.