Thanks 2oldnslow ...that is exactly the answer I was looking for - I'll go the AGM route this time, sealed and no maintenance because mine is same place as yours - high in rear of an 845. Will see if I can find two that fit if I set them on side ... but tried that before and no size fits two.
I have a wet one - 27 - now, a PITA to check and add water, and is probably what killed it - got five years tho. Will look at Trojan, and the others you mentioned this week and see the sizes that will fit in the box ... Dead as a door nail, and drops charge in two days with zero load.