a mini with zero floorpan and a spacefram setup is a tad diff to a clio which is larger, made of heavier components, has more components, more loom, stiffer front end (more metal).........then you cut out the one light part (the floorpan) and replace it with 50m of steel tube, an engine, diff, trailing arms etc etc.
reliability.......an gearbox designed to pull 150kg then has to pull a ton + 2 massive contact patches for drive.........
all in all a dumb and expensive idea.