"Baggage door" advice

[TimC]

I'm building a tongue box for my son's td. It'll be the commonly seen wedge shape about 7" wider than the tongue on each side (not the one pictured). 48" wide at the back, 29ish wide on the front, about 8" or 10" tall. The top will be stationary, non-opening (bike fork mounts on top). I am going to build side doors. I've searched for commercially made "baggage doors" but have found none around 8" high and 20" long. So I'm going to attempt to build them. Does anyone have an example of a waterproof (water resistant) door they have built?

One side will have an access door for the batteries and another for the battery kill switch, 12v charger and solar charge controller inside and a 120v port and 12v solar port mounted on the outside. The other side will have one larger door to store the solar panels (20"x24"x3 suitcase).

Pictured is my slapped together tongue box on my woodie. The door and living hinge on my tongue box works but is not completely waterproof. Not a big problem as I can just leave it open to dry out. Never gets more than a little water inside. It is hinged on the bottom for easier access. I just want to do something a bit more attractive and more water resistant for his tongue box.