Hi. Why don't you use your Thule Cargo Rack to mount your future Solar Panel? I did and it has been a great solution, too. My battery bank was located in the back of my TC, as well as the Cargo Rack too. This proximity made it very simple to route the necessary cables and some room in a cabinet for the monitors.
This is a link to a previous discussion of this type of solution;
Maggie Roof Rack PostMy Thule Rack (Maggie Rack) solution;
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If you are just trying to keep your battery from being discharged, during a short time, just disconnect the battery cable (-) lead from your battery and hit the disconnect switch that should be in your battery cabinet. If you are only leaving it for a month or two, typically you will not have sufficient discharge to be an issue, if the SOC was current at time of disconnect. The best solution would be just to remove the battery and take it home and charge it, periodically or put a trickle charger on it. It really comes down to whether you have the $$, Time, or wish to deal with the hassle of removing/reinstalling your battery.
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