Ndoctor, I understand what you are saying about the additional time, but I have a LeLuv air-pumping cylinder, with a clip-in fitting for the hose and gauge, and I can use it to water pump. I just fill my 2 1/4" x 9" cylinder with a couple inches of water (you need to experiment with how much water to put in), and without the hose attached to the cylinder the water will not leak out. I then stand with the cylinder pointed down, insert my penis into the cylinder, get a good seal using coconut oil on everything, sit down and point the cylinder up, hook up the hose, and start pumping. I can sit in my chair, or wherever, and pump without losing any of the water. The only thing is you have to keep the cylinder pointed up so no water gets into your hose, pump, and gauge. If you do need to be able to point it down you can disconnect the hose and the locking hose connection will still keep the water in without leaking out. The only thing with doing that is you won’t be able to monitor any pressure drop.
So you see Ndoctor it can be done with only a slight increase in time. When it comes time to remove your penis from the cylinder you’ll have to keep the cylinder pointed up, gradually release the pressure over a 30-45 second time frame keeping the cylinder pushed firmly against your pubic area, remove the hose, point the cylinder down, and then remove it. Water loss will be very minimal, and you will be able to water pump with an air pump without damaging it. Try it and let me know if it’s successful for you, without taking up the bath, or bathroom.
Note: You must have an air pumping cylinder with the locking hose fitting for this procedure to work.