I need to put heat in my shop and was looking at this from Home Depot. My shop is 30 X 16 with r13 in the walls and r19 in the cieling on a slab. It is detached at 125' from the house. I have a sub panel with plenty of room for more breakers. No access to gas or propane and a heat pump is out of the question. Anybody have any thoughts. This has become my full time gig, so I will be out there all day every day.