Simon Gregory's design is probably easier to copy!
I would suggest it is still worth considering a couple of baffles in your tank even with a sump - just to prevent around 25kg of fuel (half a tank) sloshing from side to side when driving quickly through bends.
A good fabricator could quickly cut two thin slits into the top of the tank, drop in a pair of thin aluminium baffle plates with holes in to divide the tank into three compartments, tack weld them to the bottom, and them weld up the top slits. This should not take too much time?