Only things to watch out for are 1) do never hook it to one full and one empty block2) make sure you charge the blocks in pairs again with a 12V charger (or the built in) before you use your tractor.
I didn't mean the tractor built-in charger, never user that on a pack that has some blocks discharged while others are still full. I meant the charger that may come with the 12V->110V inverter, some do have a charger built in (and hence are basically a UPS once you add your battery).
Hope this makes it clear. Markus