SOLAR + KeyLine VSR Offer Reliable Battery Charging & Outside Storage Protection
I know you are in a hurry, but you already reached the best conclusion on your own.
So in the future, circumstances such as these begs for a solution, which if you had more time you could accomplish.
Have you ever considered adding 400W of solar to your roof? These kits by Renogy are mostly affordable; and if you ever connect with a RV type of handyman, you might then consider it.
In the meantime, you can watch some YouTube videos on the subject to get familiar with the concept; and then I would recommend you look into the addition of a Keyline VSR so your solar power can charge both your house batteries and your engine batteries.
This combination of solar + solar controller + VSR is not only perfect when you are using your RV; it's also perfect for anyone who stores their RV outside; and wants to protect their house and engine batteries from going dead in storage.
For more information you can do a search by typing "imnprsd VSR" in the above Winnebago search bar or copy this to your browser search bar: "imnprsd VSR site:winnieowners.com"