Putting Model A on battery tender

[Gary loves Fords]

I have a question on charging my 1931 Model A Deluxe Phaeton. Can I put the positive clamp on the starter bolt and the negative on the frame, to keep the battery charged, without having to pull up the floor board to charge it? I am not real good with electrical chores. It seems my A is wired up in such a way, that the motor has to be be running for the lights and horn to work. It's the first A I have had that needs to be running for them to work. Any help will be greatly appreciated.