I went to a metal shop and had them cut me some "L" stock for me. I can't remember off the top of my head how wide I had them cut it. But as you can see it's not that wide. I just measure the amount of width I had to work with to center my holes I had drilled. I just replaced the existing bolt that went into the T-nut that's used to mount the bracket. I just got something a little longer to accommodate the new bracket. I made a little template so I could have the holes drilled correctly for the awning to mount to.
In the first pic you can see how it's holding it on. I believe it's a 4" by 4" L stock that was used.
Good thing to note in this pic. I ground off a bit on the inside part of the bracket to clear the weld bed from the main basket bracket. When I held up the bracket I noticed that it wouldn't lay completely flat because it rest against the bead just a tad. I just took a grinder to it and made it look nice. I made sure to do the other to the 2nd bracket. Just make sure you mirror it and not the same side.
In the end they came out really nice and look good. Plus you can't really see them anyway, but at least they don't look hacked. I looked all over for a universal bracket but nothing would work for actually mounting to the trailer unless you started investing money into the really nice aluminum brackets that bolt to the basket. I didn't want that. Also make sure when you mount the awning that you don't go too far back to where the hatch will hit the awning. I left my hatch open while I installed mine for the most part so I know I wouldn't run into any problems.
Hope this helps. Let me know if you need any other pointers and I'll do my best to help.