Onan RV QG 4000 Mechanical Issue and No Start

Until the motor starts and reaches operating temperature, all that smoke you see is uncombusted fuel and lubricants. 95 PSI compression tells us that the valve train is working, although the timing is not certain. You're getting Spark, but the sparkplug is getting wet. Maybe there is flooding due to a carburetor float sticking? Try cutting of the fuel supply and try starting with what fuel is in the bowl, maybe with the help of ether sprayed into the carb. If at that point the motor is showing signs of life, you can reconnect the fuel and proceed from there. My RV generator experience is with diesel mostly, the bulk of my gasoline/LPG experience was on the job at the phone company where those Onans absolutely had to start 24/7 365. Once the generator failed in a similar fashion as yours leaving me aloft in an aerial lift. Fortunately, there is a backup 12V electric hydraulic pump for such events. Unfortunately, without power for the air compressor, lights, heat and ventilation to the adjacent utility hole (manhole for you old timers), another truck had to be brought in. The rebuild revealed a worn valve train including push rods and carbon buildup (we used bulk fuel from Petro-Swill).

As far as suspected low compression, spritz in a bit of motor oil into the cylinder prior to doing a compression test holding the throttle wide open. A significant increase in pressure will indicate worn piston rings. That test is more telling once the engine has been running a bit and warmed up.