Your idea would probably work but I would have concerns about the amp capacity of the outlet, it's fuse and wiring. The outlet also needs to be "always on" and not require that the ignition key be on or in the ACC position. Personally, my advice would be not to do it that way. A direct connection between your battery and the maintainer would be safer and more efficient way of using the maintainer.

Nonetheless, I suggest that another and, IMHO a better, approach would be to install an LSL's Trik-L-Start or Amp-L-Start. Both are designed to do exactly what you want to achieve, the Amp-L-Start being a higher capacity version of the Trik-L-Start:

LSL Products / LSLProducts.com - Problem-Solving Gear & Gadgets

Once installed, it's always there, ready to go. It will also work if you have, or ever install solar panels. I have an Amp-L-Start.

Bob: Ihave a 2018 View 24V and since the coach battery can not be trickle charged with the house batteries when stored I plan to trickle charge the coach battery with a battery maintainer through the power outlet located below the pullout tray in the dash. I see others have done this. Are there any draw backs to doing this rather just pulling the coach battery disconnect and letting it set. Another owner runs a batterymaintainer from the 120 outlet by the couch and plugging into the 12 volt outlet in the dash however this requires runnig the inverter full time and leaving the house plugged into power which as I understand from my Winnebago literature is a Nono the inverter should only be used as needed. So if I leave the coach battery connected, hook up a maintainer to shore power and plug the maintainer into the 12 volt supply in the dash will that keep the coach battery charged up? Are there any negatives or harmful outcomes of this practice?