Dual Gas Tanks: Converting electric valve to manual valve

[dyno]

Hi,

I've had nothing but problems with my 1980 k20 dual gas tank set up. It's got the electric solenoid valve with 6 ports. I use the truck for hunting and don't trust the damn thing so I'm thinking of converting to a on the floor manual selector valve.

The only problem I can see is that each tank has 2 lines, one of the lines is a smaller return line to prevent vapor locking (i guess). If I did away with that line and just ran one line from each tank to the selector valve would I have problems? Would vented gas caps help?

Thanks