That's pretty much the conclusion I came to, it's not very practical to try and squeeze 110volt power out of a CUT's battery/ alternator.
To drill that hole you better keep your engine running at high rpm's to keep the battery up.
Those larger inverters are not cheap either, might as well get a used PTO generator, then you could make all the power you need.
I know that is a big leap from just wanting a little ac juice out in the field once in a while.
I have a tiny little plug in the cigarette lighter inverter, I use it for my camera's battery charger, cell phone and blue tooth ear piece charger. Mine has the usb outlet which is handy for those cell phone acs. Not sure if mine would power a laptop, looking at my laptop's power supply charger it says 65 watt output at 19 volts DC, and 1.6 AC amps input.
JB