Depending, a 1000-1500 watt inverter would allow you to print to a lightweight (compact) laser printer in the vehicle.
I have a setup just for that purpose, although I’ve only had to use it once (and not as a notary/NSA).
It’s not a good idea for regular practice, but it may be handy in a pinch.
Depending upon how you have it set up (on a rolling case/cart), you can even bring it into a cafe/restaurant and print using building AC (throw a good tip).
But, if the lender/seller/etc. does not get the docs to the NSA timely, they deserve to pay a premium for mobile printing and/or have to deal with the delay of printing at one’s fixed base.
HWB.