Firstly, Welcome to Ribnet!
This is an interesting equation - you say your garage is 5.5m long. There are trailers with removable drawbars, but unless you want a huge faff every time you take it anywhwere, it's probably best to look at the whole rig:
- What is your tow vehicle? if it is a big heavy thing, you could go unbraked up to 750Kg, which instantly shortens the distance from winch post to Hitch by about 0.5m, BUT, a 4- stroke outboard will eat into that weight allowance, and also do you want to future proof against a smaller car? (in both cases pointing towards brakes). An unbraked trailer will give you about 100 extra KG to play with on the boat, but that is likely to be irrelevant if your car can only tow 600Kg unbraked.
I assume it's a double door? I have a double garage - but with two single doors, which restricts beam somewhat. (there are a lot of 5m & smaller ribs out there at >2m beam) Then of course if you have a smaller rib, you don't need the monster engine for the same performnance, again keeping the weight down & shortening hitch length by going unbraked....
So, lets assume you have to go braked. One big thing to remember is that for most boat trailers "boat length" on the spec. sheet assums a solid hull. Net result is inevitably on a rib trailer you get 200 yds of drawbar hanging out the front! (Your toobs will be approx 0.5m diameter, and the cones at the rear will likely hang out a similar distance give or take a bit too, all of which doesn't need a roller / bunk under it - so you can actually get a trailer designed for a metre(ish) shorter boat than your rib! (which is what I did).
Just for the "pot" I got what is now sold as the Humber O-Pro 2m beam, but my garage is a single door & has an extra 2o cm on yours. (you did measure to the door and not down the side wall?)
Somewhere I have a summary of rib weights / lengths etc for when I was looking to go bigger. If I can find it I'll post back with a list of anything sub 5m.