the sub frame is a weak link on this bike. look into having one fab'ed. build pannier mounts as well, wether you use hard or soft bags. is there another way of adding oil capacity ? ala what other bikes use? ( xr crf style ) that wouldnt run as much?
the xr400 would be an idea RTW mount. as is a DR350. both tough as shit. simple, lots of parts, cheap, fast enough. as you are aware not a good idea pulling race speeds in a 3 rd world country. as you and another mentioned many over pack, so they need a land barge. that would kill alot of fun.
have you checked out horizonsunlimited.com ?
hhhmm, find a fab shop in poland, ( lower costs there right?) make up several sub frames that can handle more weight, sell 'em here, pay for your ale on the trip.
I'd need a friggin seat remake first, you're tougher then me if you can handle that stock wood plank.