Welcome to the Forum.
You didn't specify what brand of awning you had and if its the upper or lower brackets. Zip-Dee's have straight arms, Carefree has curved.
Both of the Vintage trailers I've owned had the Carefree awnings. The lower brackets on both trailers were lag bolted into the plywood floor. I suspect Zip-Dee is the same. Both floors had rotted from water entering the loose mounts. The brackets on the Tradewind were bolted on top of the trim strip making it even looser fit.
With the TW I had the interior skins off and was able to bolt the mounts directly to the “C” channel after cutting back the trim strip. I used stainless bolts, thread locking compound and Tempro sealer.
If you're not comfortable loosening the lower interior skin you could use lag bots and locking compound to screw into the channel.
Depending in the condition of the floor you also may be able to drill out the existing holes to larger size, fill with epoxy and plug it with a dowel rod and remount the bracket when its cured.
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