I had to go back and edit two posts about the radio hookup. It is not hooked up under the seat. Something is, with a red wire, in conjunction with the Kwikee step IGN signal. But it's not the radio.
The radio play mode (red wire on radio) is powered off a brown chassis wire behind the radio. It came from a 4 wire plug, which now has only 3 wires remaining: Red/white, black, and white. The red/white is always hot. The radio does draw power whenever it is available, even if the radio is not turned on. The clock and all the feature messages are displayed.
One way to have the radio available at all times, but with power management, would be to wire an on-off switch from the red/white chassis wire, and feed the radio from the switch. Then use that switch instead of the radio switch.
Alternatively, the (non-GM?) power mirrors run in the ACC mode. A person could track that supply wire down inside the cab. If R-Vision added the mirrors, it probably isn't fused, lol.