Lipo ballancing connector to power gimbal

I was wondering if it would be harmful in anyway to my gear to use both plugs on a lipo. main connector (JST) to power my fpv transmitter/cam and use the balance connector to power my 2 axis gimbal. In the past I had powered all the secondary components(cams, led lights, gimbal etc.) with a secondary 5v pdb. Recently, having a nagging feeling that my fpv transmitter and gimbal were under powered, I looked up the specs on the fpv trans. and the gimbal controller. Turns out both of them were supposed to be powered by a 12v 3s lipo.
So, what it comes down to is my secondary lipo which used to simply connect to a pdb, is going to be need an additional 12v power source. I have ordered a pdb that has both 5v and 12v output sections. But in the meantime, I trying to decide weather I need to add a 3rd lipo to my quad. Or maybe I should just leave the secondary gear(lipo, cams & gimbal) off until I can upgrade to some bigger motors, props and a higher cell count battery. As it is, that 3000mah 3s lipo doesn’t last much longer than a song.

On another note, I currently have these flimsy 1045 plastic props on my quad. Will I likely see an improvement in flight time if I put some carbon fiber blades on there.
Appreciate your help.