When using the red caps for a bladder do you extend the fuel line down inside to the bottom of the red cap when its fully unrolled?  Or does the fuel line end at the fitting?

Same in combat. But I would recommend to add just a simple balloon around the little red cap. Caps are not s robust as the old baby pacifiers. The balloon will help protect the cap, and protect your airplane in case the cap breaks. Btw you can get the pipette bubs here and they're a bit more robust.   https://www.ebay.com/itm/172216355832

btw, last night I tried something new. I was thinking even on my fuel bulbs I'm using on my nostalgia stuff, I didnt want fuel all inside my airplane if the bulb broke. So I surrounded the bulb in a finger condom. They sell them at the office supply to be able to flip through pages. I put them around the fuel bulb so in case the bulb breaks the condom should catch it.