There is no reason you can't do it. It is a matter of personal preference but I would urge you to consider a couple of things related on who will be using the system.
- Trapped air in the system can prevent the pump from shutting off which will run your battery down and possibly damage the pump, you need every guest to understand that if they don't hear the pump stuff off it is a problem. It is a good idea to leave the system powered off unless you need it and this takes some of the convenience away.
- A pressurized system reminds people of home where they don't worry about running out of water. Depending on the user you can go through water much faster
- A faucet left slightly cracked open will drain your tank.
On the upside a pressurized system makes sense if you have a hot water heater and shower. Personally I prefer a foot pump system because they move plenty of water, keep your hands free and keep everything simple.