+xBeen for a fly this morning and experimented with how the setup works.I found out that the usb supply is actually on the main bus not the avionics, so turning on the pilotaware before the engine is actually possible, it just takes a long while of waiting with the master switch on before being able to start the engine.I might just revert to battery power for the pilotaware as I already have the battery and it easily lasts a full days flying.
I'm glad you are able to start PAW before the engine as that solves your principal problem.
Lee (on the PAW Forum) has said the latest iteration of software will boot up a lot faster.
I fly an aircraft with a Dynon Skyview and that takes a fair while to boot up. Not excessively long but certainly long enough that when it's 38 degs I want to close the canopy and get the cooling fan at the front going. So, I flick on the Master and Skyview and then do the external inspection, so everything is booted up by the time I've checked the number of wings still attached. The Skyview will draw a lot more current than a PAW box :-)