Not sure you have room to add one, but consider a fuel vent dryer. PS thinks highly of them. My older one came with glass sides so I can see at a glance when the desiccant is getting saturated. It can be rejuvenated on a stovetop
Many such vent blocks are simply low spots in the vent hose that have trapped some fuel. When you fill the tank some fuel sloshes into the vent hose at the tank. If instead of running back into the tank it runs down to a low spot in the hose, it will be trapped there forever, blocking the vent. Mine was blocked this way for about thirty years. The factory ran the hose up out of the tank top and then immediately down to the hull floor, along the hull, then up to the vent fitting at the transom. Filling the tank had to be done extremely slowly or the fuel pump would click off. After I found this defect, I re-ran the vent hose up and fastened it to the underside of the cockpit floor until it exited down at the transom. That was about ten years ago and no problems since.