George.... my 4.7 fits nicely into my garage width wise and the height of the standard sized garage door, i even had my A frame made to measure with folding arials etc so its still just scraps in :-)
A close friend of mine has a 5.4 searider and we've tried getting his in my garage, firstly we found the turning circle a lot more, as i have to fit the boat between two houses we dont have a great deal of turning space before it has to fit into the garage, secondly the draw bar and the extra lenght makes it much longer than 5.4 metres, altold its nearer to 6 + metres, also he has a higher A frame and fixed ariels, in the end we gave up as we started hitting walls and denting things.
Ribcraft advertise the 4.8 as still being able to fit into a standard sized garge, so if your garage is a standard size this is max your'll get into it without significant alterations to the garage.
Altering a garage isn't such a bad idea, i've seen one with a big hole cut out of the door which allows the draw bar to stick out when the door is shut, i've also seen a garage with a hole cut through the back wall into the garden, the boats rolled in and the draw bar slips through the hole into the garden.
Both not idea but a damn site more secure than leaving your boat out or somewhere else, remember your biggest security aspect is that know one knows its in there.