I read lots of posts here and elsewhere about repairs for my Autohome Columbus RTT before attempting to correct a small tear around my door opening. Wanted to share my repair in case it helps another.
The tear was short but in the door opening (torn by falling human, not a wear and tear issue) and I was very concerned about spread on this mid 1990's vintage tent. I wanted to patch on both sides but there wasn't a good solution due to the interior storm flap, I ended up including the storm flap for the inside repair and added patch material only on the outside.
As others have mentioned there is excess fabric around the edges of the tent under the mattress that makes great repair material.
I did not fold all edges of the patch material after noticing the cut original edges showed no fraying.
I did use 3M Super 77 spray adhesive to tack all parts in place before stitching. The adhesive is very strong and was a huge help in keeping things in place for stitching and likely adds a ton of strength to the repair. The adhesive did make driving the needle harder as it added a lot of stiction but I'd do this again for the benefits.
I used a 75% poly cotton heavy thread ~tex 100 on a back-stitch.
Happy Campin'!