All right, I'll be the oddball. I built mine 63" wide with wheels inside. I used the HF 1740 frame heavily modified. I've got 15" wheels, so the frame sat pretty high, 15" from the ground and the wheel wells still intruded into the cabin 8" vertically. I like the look of the fenders so I've bought another axle (that's 3 for those keeping count) that pushes the wheels outside the body and allows me to drop the whole trailer about 4". Track is now a massive 79", but it should look better, and this time I ordered brakes.
For those who are keeping track, you may be wondering how a 79" hubface to hubface axle will mount to a 48-1/2" frame. If you don't care, feel free to skip the following discussion. I was worried about all that unsprung weight hanging out so far from the axle mount and whether it would eventually bend the axle. Andrew also thought that this would not be a good idea. While figuring out a way to extend the width of the frame, I called Dexter and explained my concerns. The engineers at Dexter said that this was not a problem, and that I should simply use a #10 (3500 lb rated) axle instead of a #9. Since my trailer will be about 1500 lbs finished, the beefier axle should easily handle the strain.
My new axle will be done next week and the cool new fenders got here yesterday. I'd rather not deal with a wider track but the trailer will now sit down lower like it should, plus, it will look cooler.

As a bonus, I now have external wheel wells that are just big enough to hold, wait for it,... a battery on each side! Now my batteries are right along the axle along with the water tank. That is almost 300 lbs. right at the axle which should significantly lower the polar moment of inertia and make the trailer easier to turn and less susceptible to shimmy and sway.
Anybody want to buy a pristine 2K lb. axle?
GB
I'm not dead, yet. I'm feeling better.