Torque Monster !

The turbo(s) doesn't have to be in the doghouse....... Small 4-cylinder engines put the turbo as close to the engine as possible to avoid lag.
I don't see 7.2 liters as small............... And I don't see this application as sensitive to lag.
I imagine a small turbo as kicking up the torque at low rpm and creating the exhaust flow to power up the bigger turbo which will drive the tank up those long grades at thin-air altitudes; just leave it in drive,lol.
You could hang the turbos down in the air-stream or out front somewhere, I mean there's lots of real estate available.
Yeah ok a bit complicated maybe, but well worth it in the end. You wouldn't have to build log manifolds; So that eliminates a lot of the complication.
I imagine an exhaust plenum with the turbos running off that.
I think oiling the down-low turbos would be the most complicated bit of engineering to overcome, and even that shouldn't be a big problem with all the real estate under there. Ima thinking a remote oil tank, and a scavenge pump, maybe a stand-alone system. Heck, the power steering pump is right there, doing nothing but beating up the fluid; maybe you could adapt that.
Jus throwing stuff out there.