Thanks for advice.
I installed it adjacent to the AC outlet next to the stove. I did loosen the power control unit, but further than barely reaching into it on the DC fuse side. I could not remove it to connect the new wire, because the main ground wire to the panel did not allow enough slack to access the back. So, after much reaching up and under, twisting and fingering through the side I attached a new wire to the bottom most fuse position. Note, the connector screws are already backed out awaiting the conductor. Nearly an hour was spent trying to get the right combination of tools, mirror and light to 'losen' the screw! Once I realized it was loose, the screw driver worked pretty well with a final ratchet tightening. Running the wire through the seat compartments and up into the under stove area was rather easy.
Two other 'aha moments' were necessary:
The screw that loosens the front of the control panel has a square drive. I could not think of a square screw driver for quite a while until I described my problem to my wife. Upon me saying 'square drive', I knew exactly what was required. I've done decking with them several times. My cordless drill square drive ends were quite perfect!
A DC circuit does not route both wires from and back to the control panel. I noticed that only hot wires left the DC side of the panel and none returned. So, I just joined to the white negative wires going back to the battery
under the sink. Real simple.
Also installed a PD charge wizard on the converter.
Still learning, and heading east from Montana on Monday!