Frame modification questions

[Choclabnut]

I'm getting ready to have my frame sandblasted and painted very soon, but I thought I would ask a couple questions first...

Here are a couple things that I know I'm going to be doing later in the build,

1) relocate the fuel tank to the back. I've already removed the crossmember that will be in the way. Is there anything that I should consider for modifications in this area or anywhere else along the frame rails that may have a negative effect on the paint?

2) Lower the stance. I'm using the original crossmember that supports the drive shaft, and where the trailing arms attach and was wondering if it would be wise to add clearance for exhaust in this area? I don't want to see any of the exhaust when I'm finished so I'll want to keep it as high as possible inside the frame...
Is this possible without running the pipe through this member?

Again I'm trying to reduce the need to cut on the frame after it's cleaned and painted.
I'm not "C" notching the frame because I'm not dropping it so much that it's necessary.
Panhard bar relocation...
Shock relocation...
I understand that all this is directly associated to how far I drop the truck, so at what point will it be necessary to start doing these things...
4" 6" drop?
Is there something else that I might want to consider before we start spraying paint?

Thanks in advance