I don't think I like the DIY approach. Maybe it's the engineer in me but sealing air really needs the right surfaces and the right materials used in the right way. I've known enough things leak when the seals were designed to known criterea to go try the "slap enough paint on" approach. BMW must have looked at semi-liquid sealants, O-rings, diaphragms and a host of other ways to seal the tyre and eventually went for the idea of separating the mechanical and pneumatic. This is good engineering as it avoids dynamic seals (your spokes and rim flex so the seal must too) which will always leak even if you go for something like a diaphragm never mind semi-liquid stuff. For a good dynamic seal you need a diaphragm to make the seal effectively static or an O-ring type seal with the right compression throughout the movement range. Liquids have no compression and to me would leak as soon as the spokes flexed. How much is the big question.

Tyre repair gloop (basically water with suspended silicone blobs) is the equivalent of emptying the teapot down the sink. You'll think you blocked the plug hole, but come back in a few hours.....In a tyre repair the glue holds the plug (mechanical) while the rubber in compression does the sealing, hence it's a good seal.

I won't be doing this, but if you really do want to be the first (and lacking a tyre engineer to tell me otherwise), the pneumatic guy suggests keeping the rim tape. A least this will slow the flow rate if the silicone does open a leak path and will keep the seal on the spokes in compression and as static as possible.

Andy