How am I going to re-attach this jack?

^Sounds like you have a good plan, save for the concern about ripping the jacks off more than once. If this is really a concern (and apparently it is, if you remove them while in use), then making anything “too strong “ shouldn’t be a concern. Eliminating the risk should be.

bornfreeeee wrote:
Photo here of the jack on a '99 Fleetwood Elkhorn 9.5. There is some split lumber in there. Thanks!

Sorry to see that. I will be making the same repair to my TC soon too. My fridge is in that front right corner and there is some good intact framing for me to build from. I plan to get a sheet of 1/8" marine grade aluminum and fit into the corner under the fiberglass skin. One thing to keep in mind with repairs is, the stronger you make that corner attachment, the more it might tear out if it happens again. From now on, since I never use the jacks anyway, I will always remove the three bolts holding the front jacks to the corner brackets and put the jacks in the back seat so as not to rip them off again. Of course you still have to be careful loading and unloading. Good lock with it. Mountain kowboy did this repair to his 11 foot s and s but the pictures on that 0ost don't load anymore.

I had a similar issue, with the propane compartment right there, you can't go back further from the corner to get good wood. A pocket might work IF that corner will still take the weight of the camper on it.

Before investing a lot of work into a fix, I would check the overall integrity of the camper. As others have already said, there is a possibility that this is not the only corner that needs attention.
If the rest of the camper is more or less solid, a cradle fix might be a relatively easy way to get a few more camping seasons out of it.

I would build a corner pocket out of aluminum or steel to cradle the corner and mount the jack to. If you were in my neighborhood, I could help you with the fabrication

This does not look good. Everything can be rebuilt, but first you need to start disassembly, then you can assess the damage. It is frequently a lot more work than anticipated.

For a general overview, go to the Truck Camper University at the top of the TC section
https://forums.trailerlife.com/index.cfm/fuseaction/thread/tid/25966285.cfm
(or rv.net, or whatever flavor of the Open Roads Forum you use)
Scroll down to "Camper Structural Repairs". There you will find a lot of good reading material.

If the only damaged part of your Atwood jack itself is the cover, you may find a 3d-printed replacement. The jacks have been discontinued and parts are hard to come by.

I'd be looking at welded steel at each corner, running the entire length of the camper. 2X2 angle at the bottom, with 2X2 at each corner, at least a foot long. Gussets where you can fit them.

The problem is that the wood is rotted so the jack has nothing to attach to....the "repair kit" is to peel back the siding and remove/replace the rotted wood. Chances are very high this is not the only place you have rot., Good news is that aluminum siding is easier to repair/replace than filon. The bad news is that jack itself seems to be damaged now and not sure what that will take to rebuild.

What you'll find is that camper has been leaking at various places for years and this was the first place that rotted out bad enough to be a problem. If you want to rebuild, check the link in my sig for what you are likely in for. i wouldn't discourage you from repairing this be be aware of what you might be getting into.
If you look at the link in my sig to the Lance rebuild, this is excatly how it started out....the RF jack by the propane compartment gave out.

Of course you already know that will all have to come out and be completely rebuilt. Elkhorn's are noted for their water intrusion. It doesn't look like there is much to attach it to is my point. I see some dark wood, rot maybe? It looks like the mounting plate came of with the Jack the bolts are still mounted to it so that tells me of rot damage or did you tear it off or did it fall off. I'm guessing by the location on the truck you might have just pushed it off while mounting or did it just come that way? All guesses without many more pics of the damage and some detailed info. Your in the rite place though.
Joe

Bummer dude!
At least it’s tin sided, hopefully you can remove the siding easily and then you can get down to work.
Good luck!