if i had the time and the money. i would build a tank to replace the rear subframe.
Binning the subframe and the various other plastic bit's you gain a load more usably space for lovely explodey liquid stuff. Also running a Gpr header pipe similar to the original dakar bike frees up a shit load more of space you'll find.
It's been done but not with the added space from the pipe, or rather the loss of the header snaking around the rear shock.
Pros : a load more fuel with out it detracting from the looks and function of the bike, very trick!
Cons : $$$ and more $$$$$
Need the pipe if you hav'nt got one .$$
The connection the the top part of the frame needs to be strengthened, seen this break ? pretty weak link when you consider some people load there top boxes and side boxes full and then ride endless rutts for days . um more $$.
maybe i'll win that 20 mill tonite