512,
Lets look at some facts.
[1] Todays engines run thin oil such as 0/20 or 5/30, thinner than you are using, & they are not wiping out cam brgs. Even performance BB engines, Nascar engines etc, are using these thin oils to reduce friction & pick up a few HP.
[2] It is an engineering fact that roller & ball brgs will run with minimal lubrication, whereas a plain brgs needs a constant supply of lubricant. Roller rockers with needle rollers do not need a huge supply of oil. Your top end is UNLIKELY to be causing a pressure loss in the system, any greater than the factory system. The factory system uses a shaft with a hole in the bottom that lines up with a groove in the rocker that allows the oil to leaks out; you have 16 oil leaks with the factory set up...
[3] Pressure drop in the system. I have tested this on a couple of engines, with the sender mounted AFTER the oil filter & also at the end of the oil oiling system. On one engine there was a 5 psi loss, other engine no loss. There is no wholesale loss of oil pressure.
[4] As stated earlier, the idiot light is designed to come on at 3-5 psi. Would manufacturers risk warranty claims if this was too low?
[5] Engine oils. Some are friction modified. A fancy term that means the oil gets thinner as the oil temp increases & helps to get better mileage in mileage tests. In Australia, we can get non-friction modified oil that adds about 10 psi to the hot idle oil pressure. If the oil you are using is FM, then finding some non-FM oil will boost your idle oil pressure, problem solved...