Just a thought that a freind of mine in Pennsylvania did with his shop to use for painting off and on...
He found an old home that was being tore down and got the old water/radiator heating system out of it for free if he got it all out in a certian time.
He put 4 radiators in each corner of his shop and the heating unit outside in an isolated and insulated housing for it.
For ventilation and keeping warm while ventilating fresh air he put a trap door right behind one of them that goes directly outside and filtered for when he is painting and ventilating.
No hot glow or ignition whatsoever and ive been in the shop in near zero weather outside and was sweating in a T-shirt.
I know you dont have time or money to do it right now Dewey but ,I thought i'd share it with all here for future ideas for heating a paint booth area...John