You might get smaller versions made of the big military fuel bladders but Ive never seen them for sale. With petrol having a real ability to squeeze through gaps water cant penetrate, and any sort of seam being attackable by desert sand, Id say the life expectancy of such bladders unless well protected would be minimal. Military fuel bladders are static once filled.
Also, as petrol vapour is highly explosive, youd have a real hazard. Id say dont bother, vene if you could get one made.
Take nothing but photographs, leave nothing but wheeltracks..... tread lightly.