That is a really broad question. Will the tires be under the body or in addition to the measurement?
In general, I find it annoying when you can’t see your trailer. I tow an AT Chaser behind my JK, and it is not always easy to see because it is a little too narrow, however, if it was any wider, it would be nearly impossible to reach the far side for loading or unloading. I think the bottom of that trailer is about 3x6, and the widest part at the top is probably 4’8” give or take a couple by 6’.
So basically, wider is nice as long as you don’t get much wider than the tow vehicle and you have a loading system that allows access to both sides.