The main tank is a big aluminum box about 5 feet long a foot tall and about 14 inches wide, It is divided with full width and height baffles into three sections of equal area with holes in the rear bottom of the panels about 1 1/2 in diameter to allow fuel to transfer between them. I have added a sump in the center section located at the center rear, 6 inches square and, 2 inches deep.
The pickup is a length of hose that comes from the top of the tank and terminates down in the center of the sump. I used an aluminum AN 'T' fitting attached to the hose and sitting on the bottom of the sump as a weighted pickup. It cannot move enough to contact the sides of the sump walls. I would estimate that there is about a 1/2 inch clearance to the bottom of the sump from the two 'T' openings and therefore the inlet would be about a 1 to 11/2 below the floor level of the main tank.
No foam. The tank is all welded up and replacing foam would be a big deal.
I am pretty sure fuel will normally find its way into the sump while on track pretty consistently. However, I agree that a surge tank would probably solve the problem. I just ordered a length of aluminum tubing to make a surge tank.
I'll send you my contact info via PM. Thanks again, Don.