1. If the pickup location (outboard end) of the 18 gallon tanks was the problem, why not switch the tanks end-for end, and run longer hoses down to the fill, vent, and outlet ports, which would then be located more amidships?
Well, I think you would then have trouble getting the last few gallons in the tank when you filled up.
Here's a plan I had for the TyBoo22 before a couple of doomsdayers convinced me I needed more capacity to make it to Bonneville Dam. If you make a rigid platform (one for each tank) to put the tank on, and set the outboard end right on the floor and the inboard end on an appropriately sized shim block to make it level, you would eliminate all the little problems. You would even have the added benefit of being able to rinse off the floor beneath the tanks. Depending upon how stout the platform material is, a shim block in the center of each platform is an option. My plan was to use 3/8" polycarbonate sheeting (Lexan type stuff), which would have been stiff enough to bear the weight and would last as long as the boat.
That being said, however, I still think the tank upgrade (even a pair of 20 gallon jobs) is well worth the expense.
2. Are people using the Tempo plastic p-traps available in the West Marine catalogue to prevent backflow of water through the vents to the tanks, or the anti-siphon vents also advertised there? Or something else?
I know several folks have put these gizmos on, but I never saw a need for them. And the TyBoo22 got slapped by some pretty good water, too
3. Has anyone used the Tempo or Todd under-deck tanks advertised in West Marine (They have side-saddle tanks, as Les has noted--anybody tried them?).
Not me. However, I am surprised that you haven't snatched up some kind of portable tank already to get you back in business until the real stuff gets here. You could always use it for the times you want to carry extra fuel.
4. How exactly, do the pickups work in these (18-gal) tanks--are they simply a tube from the bottom of the tank to the outlet fitting at the top of the tank, or what? Could they be removed and extended, bent, directed to the lowest point, whatever is necessary?
The pickups in the 18 gallon tanks I had were rigid tubes sticking straight down to near the bottom, with screens on the ends. However, the new tanks came with suction hoses that were longer than the tank is deep, and just layed on the bottom. I reckon you could do that with the pickups on the 18's and get away with it, but something about the idea has always bugged me.
5. When I reconnect hoses to tank fittings, would it be good sportsmanship to use a little oil or Vaseline to get 'em on easier, or is there something bad that might happen if I do?
Naw, oil or grease will stay for a long time and make the hoses more apt to get pulled off. The best way is to spit on 'em. That makes it slippery enough to get assembled, but goes away quickly. Having been without your boat for so long, you'll probably be mad enough to spit pretty good by the time you get it back together.