I'm assuming you are going to travel with the dish in place ? Maybe not ?
The problem I see is you're not able to see what's under the roof.
We are not sure what's under the roof where you plan to install the mount.
If the mfg supplies the hardware then the mfg accepts partial responsibility (liability) of the mounting. Being you are mounting it and not a paid installer, you assume the other half.
As you probably already know, you have to be very careful as to what you use, how deep you drill, into what you drill and if the structure is solid enough to accept it.
Ex: if you had a leak around a roof vent and it soaked the surrounding framework and the wood was compromised , then the hardware you use might not have the bite it needs to hold in gale force winds.
I went through this a few times with people already and some decided to just use it as a portable dish and place it on the roof if needed. That's what I did and that's how I use mine. I just felt it might be one less potential problem down the road. You get to the point where you just don't want to have deal one more rv issue.
If it would help decide, some of the truck camper people use a 3m product with no holes to drill to hold solar panels and such.
AFAIK, they have had good results. Im not sure how it would work on other items like a dish.
google search 'rvnet, truck camper 3m tape for solar roof installations'
you should get some rv.net links that might be of help .
Good luck with your project.
