well it's important to keep an eye on the pressure to make sure the pump hasn't failed or something. It's your only failsafe to stop the charger being wrecked if something goes wrong with your standalone supply.
I'm about to put my entire kit up for sale which includes everything you need, including wiring, suitable gauge and everything.... I'll be putting it in the for sale section tomorrow, need to get some pics of it first, literally have just removed it from the car...