Dry sauna using heat gun
That's fairly silly.  Of all the consumer electric products on earth, heaters are inherently the least expensive.  That is to say you can get cheap, good ones.  


A 1500-watt cheap tossie is $12 and will last a year. 
A quality oil-filled heater is $40 and will last 10-20 years.
A proper, fixed-installation 2000W baseboard heater is $50 and will last 20-30 years.


So it's silly to misuse a tool for not its intended purpose, when the right stuff is easily affordable.  

Even the wiring will be inexpensive, and I hope you'll do it right rather than hork something together with cheapie extension cords which are not rated for 1500W loads.  That's how the recent Oakland fire started.