Any trailer made for road use should work.
Yes, even a trailer with 8" wheels will run at highway speeds. Years ago, thats all we had.
Perhaps a utility trailer would be beneficial, a you could use the trailer for more than just hauling the boat.
If you are going to use the trailer to actually launch the boat, then you might want to stay with a watercraft trailer.
If you are putting the trailer in saltwater, then consider an aluminum trailer, or galvanized. But still plan on rinsing the entire rig with freshwater after each use.
Sometimes you can find a deal on a pwc trailer, that could be adapted to your inflatable.