A bd35 you are looking at just under 400 btu per hour and the bd50 at just over 500 btu per hour. Now that is with ideal condensing temperatures . So you have to insulate to at least R30 for it to work efficiently . Your target goal is to keep your box at your required temperature with a 50 percent duty cycle on your compressor .

Yes, I am going to build my own system from ground up. What is the btu/hr capacity of the small Danfoss compressors?