I think I read this tip here, but don't remember for sure.
Do you know how tall your trailer is? Ever measured it? If you did, can you remember it? I finally got around to actually measuring mine. But I knew I might not remember the value when I needed it the most. I thought about putting a sticker on my dash, and that would work okay. Then I read this tip on the internet. I printed a label with a mirror image of the measurement and stuck it to the front of the trailer. Now I can see the height any time just by looking in my mirror. I took the picture below while I was driving.
Not a bad idea! I'm assuming you made the reverse numbers yourself?
I did my own version of convex mirror mounting. Hard to mount an auxillary mirror when I reverse and rotate the primarys from wide to narrow with and without the camper.
I'm a big one for marking easily forgotten information with labels. Tire pressures (TP65 ... got that from the Air Force), fluid types & capacitys, drain plug wrench sizes, lugnut torque, tsp of bleach for fresh water tank refill, light bulb replacement #'s in the camper, etc., etc.. Saves a lot of time when you're in a hurry, or in this case viewing a "LOW BRIDGE AHEAD" sign.