Glad to have you here in the forum with us.
Good luck with this daunting project.
If you do an internet search for "used rv parts" you will find several salvage yards that may carry the parts that you need.
Tony & Ruth........... FMCA#F416727
2016 London Aire 4519, Freightliner chassis, Cummins ISX, 2018 Jeep Wrangler Unlimited, Blue Ox Avail with AF1. TST 507 TPMS