Quote Originally Posted by Diverdaniel View Post
what if you blow an O-ring on your last tank and the other 3 are empty?
i would leave at least 350 psi in my tanks just in case, mark my reguloators so i know what comes from where, so there will be no doubt i would not wish to take a useless reg in to my mouth when i have no air.
Id go a step further and not breath any tank down at once. If you swap regs every 10 bar you will always have around the same amount of gas in all your tanks and your turn around point is easy to work out.
As for the streamlining them have you ever tried sidemounts? Dive Rite do a kit for the Transpac 2 system that works great. Holds everything nice and close but aslo out of the way. There are a few others that make sidemounted BCs if you look around. Armadillo is another maker.

Matt