There are at least a dozen RV transport businesses operating in northern Indiana, some small operators, some bigger companies that serve as their agents. It is quite likely that one of these operators would bring his truck to your location, and haul your trailer to its destination, for a price.
If you don't want to call every RV hauler in the book, uship.com can serve as your agent.
Chances are pretty good that the cost is going to be close to the figure you've already been quoted.
This is why snowbirders who don't haul or drive their own RVs to a winter destination usually leave them at the winter location, either on site or in storage locally.
I think the problem is that the cost of moving whatever it is, is greater than the value to you of having the stuff with you.
One option would be to do what non-RVing snowbirds (the great majority of snowbirds) do: keep whatever you need or want at each end of the trip, at that end of the trip. Most of the Michigan - Florida snowbirds I know move only a suitcase full of clothes back and forth, and maybe ship a few boxes from time to time. Just what the airline lets them carry, or for those that drive, what fits in the car.
The cousin who hauls his fiver back and forth, leaves his Florida boat in Florida and his Michigan boat in Michigan, rather than trying to move one boat back and forth.
Considering the cost of shipping big toys, it doesn't take many trips before having duplicate toys is the more reasonable option.