I have a similar problem getting my RIB in the garage.
If your garage roof is higher than the door, like many are just lift the front of the trailer till the transom/A frame is low enough to go through the garage door. Once inside where it higher just raise again. I aslo use a folding VHF antanna.
This works with me, i just have to deflate the tubes and pull my RIB forward on the tailer as well.
My RIB is a 4.8 but I dont think that the A frame would be that much lower.