Truck mounted RO for window/pressure cleaning

[av123]

Hi There. I have created a RO system on my truck and I have a couple questions. First off, let me explain it. I need RO water for mixing chemicals and for window cleaning. I need to travel with it, so it's on my truck. It consists of: Water inlet to sediment filter - to carbon filter -to 330g holding tank with dechlorinated water. I also use this water for pressure washing. This water is also used to then feed my (2) 8040 Toray membranes plumbed in parallel with my 15g a minute ag pump rated at 560psi. Specified pressures for making permeate are 150psi inlet, 125psi outlet. These pressures do not make a lot of permeate, and in talking with Toray, they suggested I bump up my pressures to the mid 200's. However, I'm going to need to upgrade my pressure lines because I specified everything for the lower pressures with some headroom. The lines coming off of my RO's are 1.5" grooved stainless steel. I am coupled to the grooved stainless with grooved schedule 80 PVC. On the outlet side I have fabricated a schedule 80 1.5" drain line that goes to suction hose rated at 150 psi - I don't trust it. The suction hose (that I'm using as drain line) goes to my back pressure valves. 1 valve returns to my raw water tank, the other to discharge. I also need to make another higher pressure manifold with a pressure gauge for the end of my drain line. My first thought was to do everything that is pressurized, in schedule 80. My plumber friend suggested copper, because he didn't feel the Sched 80 PVC would hold up over time. If I go the copper route I should probably go type K? My other thought would be to go all grooved stainless, but I'm having a hard time tracking that down. As it is, I'm making 10 gallons permeate every 3.5 minutes. I'm trying to double this. It is a close loop system, as I am reclaiming my concentrate water. Thanks for any ideas on which pipe materials to use for the pressure part of my system. On the feed side, I am coming off of my ag pump with 3/4" ag hose rated at 600psi, that is performing well.