Not sure what you mean by a pump bypass. As you stated, without the pump, there is no way of getting water from the tank. I am not sure what year A/S moved from pressurized water tanks to pumps, but I know it was prior to 67, so your unit was a pump based system and without a pump there is no way to get water from the tank, let alone pressurize it. The way you have it layed it is the way the new A/Ss are setup.
As for the inline regulator, I would still install a permanent regulator (not a high dollar item). This is now standard equipment on new A/S. This way, if you happen to forget to use the inline, your new plastic plumbing is still protected. I also use an inline back at the faucet to protect the water hose from high pressure, so we are double protected. Water leaks are the pits, so I really believe in doing everything to avoid problems in this area.
david & bret
'02 Bambi LS
'99 34' Limited
Air Forums # 2159
Past President Heart of Texas Camping Unit
WBCCI # 7548