Not too bad, I'd still suggest a bit lower if you can to cover the deviation of the thermometer. The rest sounds fine. I would suggest that if you have really radicle temperature variations a lot to get a Tstat or place the enclosure in an area where the temps are stable around 80 then work on setting the UTH and rheostat.
If you are decide that a Thermostat is in your budget I'd look at the bottom model Herpstat (spyderrobotics) or the Helix (helixcontrols). They are both about 100 bucks (herpstats just went on sale I believe I am not sure what models....) They are a no worry type of device set them and done.