Hi andrej!
best filtration for sand conditions will be the original storm m-240 ("sufa", as we call it) HD air box with the standard HD paper filter.
an HD 3-row radiator from armored-model sufa will be great for the desert conditions. dont forget to take spare rubber-hoses...
the front dana30 is not a super-strong axle with tyres bigger than 31', but if you will be gentle with it, i believe it will not break.
many of us here in israel have a not-so-good experiance with the ARB selectable-locker for the dana30... an full-locking automatic locker such as Lockright, Easy-locker or No-slip in the front such as in my-own sufa, is not recomended for this kind of race-use because of its bad influence to the steering in 4 wheel-drive mode... any way, this is a high-speed-race, not a super-slow rock-crawing, so i think Front limited-slip such as trac-lock or detroit true-trac will do the job.
in the rear, and for every off-road application i can imagine, i will always prefer the good-old super-strong detroit-locker over the troublesome ARB locker.
dont forget a strong-built FIA roll-cage...
good luck!!!
dror