Just as a follow up, I had the local RV shop install another 100 watts of solar and 4 - 6 volt Interstate GC2 house batteries. The chassis batteries were acting up as well, and I suspect that something on the un-switched chassis side is on. I looked at the usual suspects (basement lights, heated mirrors, backup camera) but nothing was on. So they're load testing the chassis batteries and replacing them with Grp 31 AGMs if necessary.
I'll post pics of the install when it's done. I had the shop do this because they could get it in this week. I hate having to pay for something I can do myself, but I really don't have anywhere to work on the coach myself.