You're definitely limited with the TDV8 Bernard. We've heard of some owners swapping to the smaller brakes from a TDV6 and then fitting modified 18inch rims but that's not exactly legal. Start with finding out what modified rims you can fit and then look at tyre options. Keep in mind the rear wheel arches are smaller than the front and you will get scrubbing there if you go too big. You'll usually find you need to cut back the inner front guards as well and potentially shorten the overhang on the front chassis.
Misadventure 4x4, how much stuff do you break on the RRS? I'm looking to possibly go to a RRS/D3 platform as my next but got a bit scared off from local parts prices compared to overseas with my last D2 ownership.
We've been fairly lucky given the hard time we've given the RRS. We've broken a CV twice but on one of those occasions our traction control system was playing up on an epically rough section of track so it was a compounding of problems. We snapped a half shaft and we had to replace the steering rack after a pretty rugged 100,000 kms of really gnarley stuff including lot's of Km's on corrugations. All in all not bad.