One of the generators I'm looking at is the Champion 2500w dual-fuel. I sent their support a question on what do these gennies need here's their response, "-1/2 PSI with a flow rate of 76,000 BTU/hr. under max load."
that would be a regulated supply, but 1/2 psi is higher than normal for gas appliance use.... normal would be 1/3 of 1 PSI which is about 10-11 inches on the water column scale..... BUT, im not saying that going either way with the pressure a slight bit wouldnt work in the engine of the generator, because the propane carburetor on the generator is ANOTHER regulator, which is automatically and dynamically adjusted to the needs of the engine, while it runs.....
BUT... the higher pressure would NOT be fine for an appliance that burns with a flame "open to the atmosphere", as too much pressure would not allow the gas to be carburized correctly for a clean burn..
a lot of portable bbq's operate on full line pressure, because most portable bbq's have the regulator incorporated into the control knob, which, if thats the way your set up is, you will only need to T into the HP gas line with a regulator for the genset.......
otherwise, you may be better off running a parallel line to run the high pressure gas to where you need it..... personally, when i have a portable genset that I have to haul in the pickup or unload from a compartment to use, I will move it as far away from the trailer as practical so i dont have to listen to it run....
I do have an onan onboard, but most times all we need is my little 800w generator to recharge the batteries....