I've never seen that type of CHE before, but I don't think it would be any better than what you've got. 150 watts is 150 watts.
I think part of your problem is that you are trying to heat 4 feet of air when your tortoise is probably occupying only one foot or less. Where are you? What are your night temps right now? How well insulated and sealed is your box? What species and size? Why are you heating the night box to 91+ degrees?
I've had good results in that same size box using a radiant oil filled heater. I make a little raised shelf for it to sit on so it doesn't take up any floor space. I run them on the lowest setting with the dial turned all the way up, and I use my own separate reptile thermostat to control the temp in the box. You can see it here: https://tortoiseforum.org/threads/the-mother-of-all-tortoise-boxes.20527/#post-182171
I refine the design each time and they keep getting better and better. Here is a more recent one:
https://tortoiseforum.org/threads/double-door-night-box.129054/