A 14’ width is going to be a problem as well. You will lose almost a foot on the inside for poles, so you likely won’t be able to put the slides out. Mine is 16’ wide and I wouldn’t go any narrower unless you absolutely have to. Your rig has the advantage of allowing pretty good access for packing with the slides in, but your next one might not.
Get the engineered drawings done. I have 16’ sidewalls and there really isn’t a lot of room to spare for the door or for working on top. If you ever decide you want a 5th wheel, you will wish you were taller.