Chris, from my experience, the TN battery is a much better location for being able to work on it. The older Ford 4000 and 4500 TLB that we still have has the battery on top the motor and it is a pain to access with the loaders on them. The TN has it in front and makes it easy to get to, just pop the hood and your there. The 7710-II has it below the right side cab door and it swings out but you have to remove the top step (just pops off). There is a latch you have to undo first also, then take the cover off to access the battery, the TN is still a lot faster to access then any other of the tractors I use.
As for heating from the radiator, it has never been a problem. In fact I have never had any problems with the batteries on any of my tractors other then the 6 volt jobbers kicking off every couple years and needing replaced.
