(these are great and many use them for cooltubes)The bake a around pyrex tubes are 14 in long. Its a diy cool tube but it's workin. EBay has them
Pinkladyeater, you can also go to a local craft store and
get a hurricane glass, just a tube meant to hold a candle
and protect it from the wind.
here you can see i DIY'ed my cooltube using 2 hurricane
tubes.
also, i'd suggest you do a test run for at least a day without
any sealed reflector, maybe you can get away without
the need for an air-cooled hood.
btw, i'm glad that article was helpful to you as it was helpful
to me.