Here is how I mounted mine (first post ever so hope it comes out well). Mounted to sides since there was more structure there for support.
I opted for the roof rack because it provided more stability and strength for the canopy and room. I could also use the roof rack for bicycles or simply a way to put a tarp across the top to reduce heat from the sun.
Still in progress. Going to take apart and paint everything black and re-attach.
1. Bought roof racks made for gutter mount. Amazon has the same one sold by 3 companies for about $100. Rolla and Apex were 2 of the 3.
2. Modified the brackets by pounding down the flange and discarding the gutter attaching parts.
3. Drilled an extra hole at bottom of the bracket for stability (triangle of bolts).
4. Made aluminum spacers (plate stock) to hold brackets a little bit proud so that the bracket would clear the edge trim. I had thought about flipping the brackets so that angle did the clearing but that would create a larger gap between the canopy and the trailer. I preferred to set it more towards the roof of the trailer.

5. Mounted low enough on wall to miss the ceiling inside.
6. Used carriage bolts all the way through the wall and a plate inside (rather than just washers).
7. Found that if I reduce the bolt size by one size I could use the same holes for both the bar attachments and the extrusion on the ARB canopy. This saved drilling extra holes for the canopy. I used grade 8 bolts to compensate for the reduction in bolt size. Since grade 8 only comes in hex and the bolts would not quite fit into the canopy slots I used trimmed the bolt heads with a angle grinder (just a tiny, tiny bit).

All of this of course depends on how the individual trailer is built (structure under the skin).
I am very happy with the results. Now just need to decide on the best way to join the back of the screen/room to the door. The room is so we can take the grandkids and I don't have to give up a comfy bed.


