No enclosed trailers, sorry.
The wood to the steel needs to have some sort of barrier. The newer treated lumber is corrosive to iron

I just apply an extra heavy coat of bedliner material to the steel. Help slow down corrosion. I'm in michigan, so all you can do is slow down rust. I use self tapping 1/4" torx head screws.
For tandem axle trailer axle trailers, a wheeled tongue jack doesn't work. A person can not push it and turn it because of the scrubbing of tires, at least not very easily.
So far, I have not found a decent wheeled tongue jack that wasn't stupid expensive. Most people don't realize that these jacks are to move an empty trailer only. I do 5 or 6 repairs on boat trailers per year because people move their loaded boat trailer. Actually have one to repair presently.