You speaking of the pics of bags and bare frame you posted earlier? I think they'd look great, especially with brown saddle and maybe even brown bar tape. If you used red cable housing it would look like a Christmas tree!

That's how I've been doing it too. So far it has worked out great, though I do check up on the spare and its glue condition every so often and re-apply glue if it seems appropriate. They will pick up dirt if one isn't careful. Whenever I have had to mount a spare and then checked it later the glue seems to have held just fine. But then, I'm not racing anyone down the back side of the Pyrenees.

One time while commuting home with maybe 4 miles to go I came upon another cyclist with a flat rear tire and no clue what to do about. There was a bike shop about 2 miles further which he had been hoping a compassionate driver would stop and take him to. (Yeah, fat chance, especially since he was waiting in a location where no driver would want to stop anyway.) I was riding sew-ups so I didn't have a patch kit with me. The bike shop was on our way so I mounted my spare sew-up in the well of his wheel, pumped it up to something reasonable, explained what I was doing, and told him to ride reasonably down the long hill we were facing. I followed him and watched the tire carefully for the first quarter mile. We made it to the bike shop safely and I retrieved my tire. (When I got home I threw a patch kit into the handlebar bag of that bike just in case I ever found another cyclist in the same boat. I've patched or pumped quite a few other cyclists' tires over the years, but that's the only time when I was on sew-ups.)