It has to get air from *somewhere* and unless your workshop is of infinite size it will be drawing that air from outside, either via a dedicated properly sized vent or (more dangerously from a Carbon Monoxide point of view) from around cracks in the door/windows/framework. That air, being continually replaced as combustion occurs, is usually very moisture laden (at least in the UK) and will, when the stove is shut down, cool and eventually deposit all the moisture held in that 'fresh air' over everything.
Of course if you can source external air, direct to the stove, and exhaust air direct to outside, and only use the hot surfaces of the stove to heat the workshop then you might, with unlimited supplies of fuel, have a cheap source of heat. Think of it as similar to a room sealed boiler hanging on the wall of the kitchen. It keeps the room warm(ish) with the heat lost to the boiler casing but despite burning lots of gas or oil it doesn't fundamentally alter the humidity levels in the room.
Such an approach will IMHO never compare to the comfort and luxury of background underfloor heating fed off the main central heating circuit of the main property, nor will it compare to solar air heaters in simplicity and zero carbon emissions.