First off, let me say that I have levels on the side and front of my trailer. Of course with my v nose, it's hard to put a level on the front so I placed it on the tongue. I had levels on my previous 2 trailers as well. I tend to overthink things, so I have a question
How do you know, when you attach the level to the side/front or where ever, that the level is level?
Yea, you can measure and line it up with trim or a groove in the siding. If you really want to get technical, measure from the ground up and set the levels. What if the walls and roof aren't square?
For me, if I get it close, I'm happy.