Generally I agree that turbos aren't very well suited for off-road gasoline applications, but what we've been kicking around for my rally VX is to use two T-14 or T-23 turbos sitting on top of either tubular or log-type manifolds. Simple, robust short tube runs with everything accessible and high to eliminate heat or dousing issues. More than likely I'll end up with a 4JG2 diesel in it, but that's down the road until the big shop is done.

With what is proposed here you'll either set something on fire from radiant heating or the cast-iron section of the turbo will crack from constantly being drenched or packed in mud, especially if you try to implement heat shields in an area that's a "catch-all" underneath the chassis. What's your plan for addressing vibration on what looks about 20' of tube? When it's all said and done you'll need the extra horsepower to offset the added weight.