If you buy a boat trailer with a straight drawbar, rather than an A-frame style, you should be able to adjust the length of drawbar.
Most manufacturers weld the component parts of the trailer (drawbars, outriders, winch posts etc.) and then bolt and u-bolt them together, in final assembly. People often believe that this makes the trailer weaker, but if you know what the shear strength of a high tensile M10 / M12 bolt is, then you'd know not to worry!
Anyway, I digress! You should be able to adjust the length, to fit it in to the garage, by sliding the drawbar 'in' / 'under' the trailer. However, this can be time consuming if the trailer is braked.
In this picture you can see the drawbar, with the winch post mounted to it. You'll see two bolts, just in front of the bow snubber, joining the outriders to the drawbar. You can undo these and (providing the weight of the boat isn't now supported by the jockey wheel) slide the drawbar back under the boat.
Alternatively you can buy a drawbar hinge. You need to cut the drawbar and bolt the hinge in place, but once the work is done you just pull a pin and swing it round each time you need to put the trailer away. Again, it will be made more complicated if you have a braking system.
The hinges look like this: