There is no right or wrong. I personally have had zero luck with increasing ambients with a RHP (unless you put the probe under the panel then you measure the probe surface temp not air temps it must be taken from the side) light systems are far cheaper and far easier than RHPs the easy solution is to try the lights and see if it works if it doesn't buy a RHP, the cost of the lights are very low (as I am in Canada the price of the lights , both, was about the same as the tax on the RHP) It seems reasonable to start cheap and work up in this case especially as it is clear that RHP to heat air are inefficient as they are an indirect heat source. Like heating rocks to place in a pot to boil water yes it works but placing the pot on the fire is more efficient.