I know T1 11 is certainly the cheap option, but Im worried about the maintenance and rotting.
Hard to beat the price but if installed in the "wrong place" it will rot QUICK ! (see Tyrant's comments).
Cheap insurance. Buy a hand pump garden sprayer or a handheld airless sprayer. Mix boiled linseed oil and mineral spirits thin enough that it will spray
(50/50 ?). Spray the BACK, at least 2 coats. Wait until the first coat is just tacky before the second coat. Then spray the front, 2 coats ! It will take 24-48 hours to dry. If you make any cuts, make sure to recoat. Also, where one sheet "stacks" about another, make sure to use "Z" flashing.
Another tip. Install a "belly band". 1x6 bottom trim that the T1-11 sits on. Again, Z-flashing between the bottom of the T-11 and the trim. You can use plain 1x6, but I would prime BOTH SIDE with an oil based primer. You can use PT, but you will have to wait a year before you can paint it. The best ($$$) is PVC rim.
If you are going to paint it wait at least a month for the linseed oil to "cure". If you are going to stain, use an oil based stain. Skip the last coat of plain linseed oil, but mix about 1 qt/gallon into the stain. It might be too thick for an airless sprayer so thin it down, but you will have to do 2 coats.