Roof Mounted Solar Panels

[hotqld]

I have installed a solar system 2 off 12 volt 200 watt panels charging 2 off 100 ah AGM batteries.
The solar panels very approx dimensions are 4 foot by 2foot 6 inches
Batteries.
My question is
These are mounted on the roof on Aluminun rails about 3 inches high and 1 inch wide.
I have glued the two rails to the ext roof about 6 foot long.

What is routine with the way you guys do it? Glue only or Glue and screwed.
I will be travelling about 600 miles next week 200 miles on a rough dirt road.......where there are some fish waiting to be caught!

If screwed do you try and find the aluminun roof beams to drill into? and how?
I have a 244 2012 funfinder.

[shadow]

I would not rely on glue alone. In my installation I used rubber expansion inserts, beleive they are 1/4 x 24 for each panel i instsalled 4 fittings, just drill into roof, don't go too deep or you'll pop though interior, marked my drill about 1/2 inch. put alot if caulk, avoid using silicon, into hole, bee very genrous insert and screw down. the swedge fitting will lock into place using roof material as the backstop.