With the gear tractors, the 3200 is a transmission driven PTO and the 3800 in independent with a 2-stage clutch.
Both will work for what you want to do, with a stationary implement. But the difference is when using something that requires the tractor moving. The 3800 has an independent PTO with a 2-stage clutch. What that means is you can press the clutch about half way, and the tractors transmission is disengaged allowing you to stop or make a gear change WHILE the pto continues to turn.
The 3200 does NOT have that 2-stage clutch. That means everytime you press the clutch to slow down, stop, or change gears, the PTO stops as well. Kinda like the old 8n's if you are familiar. This is really only a PITA if you are mowing or something. I dont see it being an issue at all with a stationary implement.
Now I dont think things changed on the 3200/3800, I have a 3400 which was the old model of these, and to allow the PTO to operate while you are off the seat, you first turn it in (while seated), make sure the tractor is in neutral, (good idea to set the brake but not required), and then get off the tractor. As soon as you leave the seat, flip it up. If you dont flip it up, the tractor will die in 1 second. But flipping it up allows it to keep running.