1/8 is 3mm I think and thats what we have to use (regs) for floor and roof (if using ali). Makes sense to me.
On the larger cars we ran the sheet a half inch outside the lower rails and the fibreglass panels where cut to fit the floor edge. This reduced the amount of water that came inside tween the edge of the fibgl panel and the frame. We ran through a fair bit of water from time to time (see my avatar).
New regs specifically state that no edge shall protrude so I will do this again making sure that the edge is neatly flush with the side panel.
We wrecked the floor regularly and when siliconed on to prevent rattle, can be a bastarx to replace.
My thoughts are as long as your bits are covered front to rear do whatever works for you.
Bought a car once that had 1/16 steel floor WELDED in, didnt notice this lil fact til we tried to strip it during prep. Now that took some replacing.... :-\
