I recently built this "off road" trailer dolly. It's for trailers that are equipped with a removable tongue. Utilizing the spare tire that is stored under the floor of our Camp-Inn, the rest of the hardware breaks down in less than a minute to a flat package and is easily stored as well. It makes hand jockeying the TD over rocks, sand, gravel etc. a breeze. The 22 inch wheel will easily roll over or fit between obstacles that would bog down my Harbor Freight trailer dolly. We haven't officially tried it out on a trip yet but I'm pretty sure it will work as good as I'm hoping.
Endo, Here is a close-up. This is the best photo I have at this time. I'm still working on the removable T handle. It will telescope within itself when I'm done for a smaller profile and easier storage.
That is what I used. I had a couple of pieces of curved 2" x 2" angle iron that I had bent to an 18" radius left over from an earlier job. It was a perfect fit over the outside radius of the 22" spare tire. I like to build and use things that have multiple purposes so I purchased the hub & spindle like yours and went to work. Now the spare tire has a use other than just sitting there....waiting.
I particularly like the clever and very effective multiple use of the spare tire.
For someone who doesn't happen to have an appropriately curved bit of metal on hand, it could be done with simple straight box section pieces with no loss of functionality (but not as much style).