A 12v pump would be very expensive for the durability and duty cycle to pump a 100 gallon tank dry, let alone the power requirements to power the pump.
Had a 30 gal sprayer with the 2.6 gal minute pump 3 nozzles and 5 foot coverage went to 60 gal with 12 foot boom with nozzles with a Hypro PTO pump and have not looked back.
At the standard dillution rates and application rates per acre you will fall short of an ideal settup with the limitations of the electric pump and boomless nozzles. I also have not found a boomless sprayer that gives me the quality application that I desire.
There must be a good reason that many of the 60 gallon and larger sprayers made use a roller pump connected to the PTO or a small gas engine.
The small electric pumps do great for spot spraying or doing small to medium yards but that is where they stop.