You may just have some bad gas lines underneath letting air into the line, and the steeper incline lets too much air into the line.
A bad sock on the pickup, or a missing pickup can cause it. There is something the way they are engineered with the mesh that helps them pick up fuel on a low tank. I've heard both the surface tension and the resistance.
I've had the tank off mine several times. The worst part is draining the fuel, and the next worst part is getting the bolts loose without breaking them. Overall, it's not a bad job if you have a second pair of hands to help hold the tank as you get the straps back on.
The j-bolts aren't available, but one of the jeep parts works perfectly.
The pickup and sending unit are at the front on the passenger side.