Rear hitch rack battery bank

For the structural strength, I'd take it by a welding fabrication shop and have them look at it. The load may be secure to the bumper, but is the bumper attached to the frame well enough to handle the load?

For the tongue weight you'll just have to judge that yourself if you can't find a scale. Hook it up to the TV on level ground, does it look like the rear bumper of the TV is the same or higher than when previously hooked up?

If it doesn't look like the rear bumper of the TV is raised a lot, take it out for a drive and see what happens slowly increasing the speed. You might have someone else follow behind in another vehicle to watch for weird movement or sway that you don't see.

Bill

You could move the batteries to the storage area and make sure it has proper venting. Having the inverter and charge controller in a sealed box with batteries isn't the best, either.

FWIW, I have five batteries inside my trailer but have installed venting so I don't have any worries. I did this expressly to locate them near the axles so that tongue weight isn't radically affected.

Many decades ago I made the mistake of putting 300 lbs of heavy parts I'd bought in the back of my Airstream.:S At 45 mph it tried to take me to the scene of the accident. This was in the days when you had to move the handle to put the trailer brakes on which I did while still accelerating. Once the swaying stopped I'll was able to slow down... stop and move half of the items to the front. Once was enough and to this day when in doubt about having enough tongue weight on an equipment trailer I'll give the steering wheel a little wiggle at 45 mph with my hand on the manual brake control to see if it's going to get interesting.

AGM batteries do not need venting and putting them close to the axles will be cheaper than a new trailer and TV. You can still use your rack for bulky items.

Here's a pic. Not very comprehensive, but the best I could do.

I see a few risks. Lighter tongue weight could cause more sway. 400 pounds on the bumper that may not support it. And all the money where it can be easily damaged by someone rear ending the trailer or backing into something.