As my 2000 trailer saga continues, I got the manual (scanned it and it should be on the manuals page if anyone is interested) l and it looks like at least the side marker lights that are on it could be original. As well, they are still available, so I'm just going to put new ones on.
They are part number PM M126A and PM M126R (A for Amber and R for Red) for posterity.
I still haven't figured out the tail light situation 100%. The parts manual (which is 2 years older than my trailer) makes it look like there is a two piece situation, consisting of a socket with a pigtail on it, and a lens that covers the rear over top of it. That's consistent with the holes that are in there, and what it looks like in the shot I saw in the manual. I found something that I think will work here
https://www.vintagetrailersupply.com/BAY15D-Bulb-Socket-p/itm-610d.htm
I snagged a NOS lens from the devil, but he only had one so at least I can know what I"m looking for. I think I can find lenses that might work, but I want one as a template at least.
It's definitely a different setup than what Myron had posted for the 1200 with the sealed one piece unit.
In other news, it appears the 2000 had optional electric brakes and mine has them. I have a whole new axle situation on order, but I might try and save the original stuff and see if I can get them working. I was looking forward to just slapping a new nicely painted undercarriage on there, but it won't hurt anything to clean up the old stuff either, probably with just some rust encapsulator and a heavy coat of paint.
Still working on stripping it down and repairing damage I can find. Could definitely use a bigger shop for this one.
Have found a few bolts that are IH stamped on the head though (although rusted beyond salvation), so that's pretty neat.