Thanks Chad
I've had a box of 120v switching breakers lying around for 10+ years.....I finally have a use for them.
In out case we have a 300w (3w standby) and would adds a 3000w. The 300w so the family (Dad like his 60" TV) can watch a movie before going to bed.
I had the thought of using a battery switch set up as Inverter 1 - OFF - Inverter 2 with the output from both inverters feeding the 110v panel. The feed from both inverters would be live when there is any 110v in the trailer. The panel in ours is up in a bedroom cabinet so switching circuits on and off would be O.K. What I like about the system you designed is one doesn't have to remember to turn breakers on/off.
Our PD transfer switch hums. Tried to tighten things up to no avail. I assumed the AC (wish it was DC) coil that is energized to keep the contact closed. What switch are you using?
Once again I really appreciated all the information you posted, Thank You