For the mileage you are forecasting it's a no brainer, petrol. That's without exploring the possibly of LPG conversions.
Alas the modern mindset is fixated on diesel, but the petrol engine is king and being revisited by folks who've been otherwise hooked.
A complicated TDV6/8 is fine if you are minted, a gambler, or an ace spanner man, but for more refinement with much more pace and little harm differential in the pocket (or purse
) you'd be mad to consider diesel.
I doubt many petrol RRS have need for body off jobs.
Btw, RRS L302 is a seperate chassis in which the body is bolted to, the RRFF L322 on the other hand is a monocoque unitary body, it's a widened, heightened and fattened BMW X5.
Get a RRS petrol and start the trend to fill these corridors with a new dimension, it's just a Dicovery 3/4 after all!!