I put the porteur bag on hold. I have all the pieces cut out but I'm still working on how to mount it to the rack so it stays on over the long run. Instead of using velcro I'm going with straps.
Instead, I thought I'd make a gas tank bag, which is made to look easy here. Of course, I made stupid mistakes, one of which was not making sure the velcro straps line up so the hooks engage the loops. Instead of ripping the stitches out I cut one piece of velcro, turned it over, and sewed it to the piece protruding from the bag. Twice. Yep, I did it to both sets. With all the other difficulties I was having this turned out to be a practice bag after all.
In the photos I'm presenting in the best possible light. You don't want to see the details. I'm not happy with the size. The next one will be longer and wider.
By the way, the frame bag did well in the rain. For good measure I hit it with the hose for a while. The towels inside stayed dry.