About the camera: my two cents. I have a wired and decent camera on both the trailer and truck. Frankly, I can't see any advantage to the camera for backing into tight spots. That said, I wouldn't be without a camera on a trailer as large as your's and mine when traveling. Mine is 35' less in length minus an inch or two.
A feature I use it the microphone in the camera. I raise the speaker volume to be able to hear DW (or other spotter). Our's might be unique situation but my DW never uses the same hand signal twice
! But, if I can get her to speak what she "wants" it sometimes helps.
Most helpers / spotters don't indicate when all is well as you begin moving, which I like to know. If they just stand there silently, you don't know how you are doing. Also, many or most folks seem to think (don't know) the truck / trailer can make sudden and physically impossible corrections.
I also find that flipping my mirrors back to normal (from towing) helps, as well as using the convex lens.
Many camping couples, switch drivers for backing. Seems as though a man can give better directions (possibly) and for sure a woman can follow instructions better (typically). I've seen this work far better than vice versa.
Funny story: I tried to help a newbie couple (camper and truck just bought) earlier this year get into a spot with limited room to maneuver; he was getting frustrated and I approached cautiously (!). I would tell him to turn one way a little and he would go to steering lock... then he cut back the other way, since he thought he knew better. I could see this going nowhere; I convinced him to let the little lady drive, and the first try we had the trailer in spot and in its most level part. She simply did what I asked. I don't how well he could direct and didn't want to tempt fate. She was so proud to have gotten the job done so easily. They were a nice couple with a couple of sweet little girls that brought me coffee twice.