Just bought a trailer for my Malahini. It's 19'8" long, and my garage is 19'7" long
However, I have 36" of straight tounge before it 'Y's out. So I will be installing a Fulton Fold Away bracket, and figure I can swing away about 30" of that front tounge. That being said, once the motor is on, I figure I may still need to go in at an angle to fit it in the garage. Maybe not, but it will certainly be tight...
As far as the trailer goes, personally, I can't weld, and don't really know anyone who I would ask to weld it all up for me, so the choice was easy... buy a used trailer.
You may be much more adept at welding, I don't know, but many people have found good trailers used, for less than the cost of the raw materials to build one.