Vent tube modification for FW tank

I'm also dealing with the same water loss out of the vent tubes and did a lot of research on it yesterday - seems the problem is in large part due to some RV's no longer having gravity feeds. The only suggestion I came across was maybe putting a shut-off valve on the end of the vent tubes. I am also dealing with a related problem in that I don't think the hose going from the tank to the pump is mounted in the top of the fresh water tank and doesn't reach the bottom. It is impossible to get to this hose without cutting some of the frame holding the tank in place, which I don't want to do - one suggestion for this was to tap into the freshwater drain hose. I am open to other ideas as to either problem.

Thanks