So I decided to follow @Fuchspk's lead and order some stuff from Fabric. I ordered these because I'm waiting on replacement cages from Simon at Carbonworks and it was pretty inexpensive compared to other lightweight alternatives.
I mostly liked these for the tool keg since I only really ever ride with one bottle. I normally throw my spare in a cut up bottle in my second cage because I hate things under my saddle. It trips me out, I don't know why, but it does. I still had to cut the threaded part off the keg to fit a tubular in there but it fits nicely, even with the provided sleeve and makes it easier to remove given the sleeve has a pull tab.
Anyway, actual weight for the studs with bolts is 7g for a set. Easily shave that down with an aluminum bolt swap. The bottle isn't amazing but it also doesn't suck. I figure once i get my replacement cages, I'll leave the studs on the seat tube for the spare keg and if I ever really need two bottles on a ride, I can toss the Fabric on the studs.