My truck has a suburban tank in it. As far as the exhaust goes it's mounted outside the frame and exits in front of the rear tires. I can get a better pic of the exhaust if you need it.
Any way to relocate your shocks with some custom brackets?
On my truck the shocks mount to the top of the spring plate, not the axle. This let me use a shock for a 4" lift with a 6" lift spring (left over parts from previous projects)