3500lbs won't be too bad. If it starts gear hunting in drive, manually select gears to keep the revs high. You'll probably be running with O.D off the entire time. I assume you have an aftermarket 7pin, I'd check that with a multimeter before you go to rent an RV. I know the stock 4 pin...
My converter is faulty as well, I took out the taillight and jack but I still cannot seem to find the converter... I'm getting desperate because I have a trailer rental scheduled for tomorrrow.
Any ideas?
Found one for $2k on partsouq, BRAKE BOOSTER ASSY, W/MASTER CYLINDER 4705060010 | Toyota Parts | PartSouq - https://partsouq.com/en/search/all?q=47050-60010
Probably still worth it even at $2k.
There are two distinct brake booster related sounds that mean completely different things.
1. You get an ABS light on the dash followed by an alarm, 99% this means your booster pump motor failed
2. You hear a loud horn like sound coming from the brake booster itself, when under pressure...
Horn sound from brake booster means internal seal in master cylinder is bad, and cannot hold high pressure fluid from accumulator. Non replaceable part, you need a new master cylinder assembly sadly.