Question: WIll 2 x Pylon tech US 2000B survive loadshedding over the next year, or do I need to order another battery? Currently, the batteries are giving me about 4 hours running time on current load.

Thanks in advance

It all depends on the load and the time it has to charge. If it is lasting 4 hours currently and you are able to fully charge before the next load shedding it should last.