An easy fix for you.
As I understand, you coach has a 10w solar charger. You also have a standard installed Trick l start.
The problem you have I believe, is that for the Trick l start to charge the chassis batteries, you have to have you house battery disconnect ON, with all the parasitic loads.
The solution is simple. Take the wire from your Trick L Start that is installed on the house battery disconnect solonoid and install it on your battery isolator solonoid. The house battery side of the solonoid. On mine its the right side looking at it standing facing the front of the coach.
What you end up with is the coach batteries will now charge from your trik L Start with the dash house battery disconnect switch in the off position.
Remember this will maintain a fully charged battery, but will not charge a depleted battery.
When you do this, disconnect the ground terminals from both your house and chassis batteries and throw a piece of cardboard or something over your solar charger.
A 1/2 hr job.
edit--I have a picture of my installation buried somewhere in my computer. If you dont completly understand what I just said PM me.
My installation keeps my chassis and house batteries up just fine.
2002 Winnebago Journey DL 34 ' Cat. 330 hp
Great wife and Charlie, Cavalier King Charles Spaniel RIP