1) While a single "skinny style" side saddle mount (NOT talkin a huge 8D mind you) 12 volt battery can start the tractor in good temps, if it absolutely MUST start at sub zero temps that may not suffice, depending on condition of engine.
2) Sooooo if I were going to use those skinny side saddle 12 volt batteries and it had to start at sub zero temps ID RECOMMEND THE USE OF TWO WIRED IN PARALELL Now that will make that Denso whirlllllllllllll
3) Starting a tractor where you need a sudden short burst of very high short term starting current IS NOT WHAT DEEP CYCLE BATTERIES WERE DESIGNED FOR. ID RECOMMEND REGULAR TRUCK/AUTOMOTIVE STARTING BATTERIES NOTTTTTTTT DEEP CYCLES..........
Hope this helps