Do not seal everything up with RTV, this will guarantee rusting.
You need to maintain the ventilation holes in all tubing so that moisture can drain or evaporate. The best thing you can do is drill a big hole at the lowest point of your BB to drain the water and condensation that will inevitably get in the tubes.
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Il faut de l'audace, encore de l'audace, toujours de l'audace
1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1