Nice work Jeff - it's looking good.
Fabric repairs in the field were normally done by doping a new piece of fabric over the hole, unless the damage was extensive, when the area would be re-covered properly, and stitched and doped.
Smaller patches (i.e. not a full 'bay' between ribs, on say, an elevator) were sometimes left un-painted, due to time and pressure of work, and these would often show up as dull red patches.