Thanks Tom. My 2000 Popular 200 on Chevy chassis sounds quite a bit different. My bat. sits underneath the rig, below a through storage compartment that runs the entire width of the vehicle, so no access from under the bed.
I did get the bat. out however. Had to remove 2 hose clamps to move the gas line out of the way, disconnect the cables by feel and with the help of a mirror, then slide the bat off the shelf (all on my back of coarse). A lot of work just to test the battery! Still don't understand the label saying remove this panel. It's riveted in place. A cruel joke by Roadtrek I guess. Anyway the bat. tested good so I've eliminated that as part of my bigger problem.
John