I agree on the 2 predator 3500 inverters from HF. Mine run perfectly had one for years and got another one and run in parallel, again with no problems. runs everything in my 2018 3920fb.
I keep mine in the back of my truck under a foldable cover locked into place with a 50ft 50amp cord that plugs into the trailer ours purr like a kitten !!
this is the Honda parallel kit that I use.
https://www.ebay.com/itm/New-Honda-G...1cQ:rk:31:pf:0
this is my back up firman that I have just in case
https://www.firmanpowerequipment.com...it-50amp-1201/