Suburban lowering help

[Ol' Drippy]

Hey there I have a 78 suburban 2wd and I am trying to figure out the best way to drop the rear. I want to lower it about 4-5 inches but still maintain the trucks towing ability so no frame notches at the moment. Extended rear shackles are a problem because they would bump up against the gas filler tube. I would love to just use a flip kit but that would pretty much put the rear axle sitting on the frame. So my thought was flip kit in rear and then reverse the shackle like the 4wd guys do to gain back some clearance, anyone ever try this? I have also contemplated de-arching the springs but I don't know anyone near me that does it. I could also just go ahead and order new drop rear leaf springs but they are expensive, what do you guys think?