New Fermentation Chamber

I just built a new fermentation chamber out of a 3.5 Cu Ft chest freezer. It will hold a 6.5 gal carboy and a 3 gallon carboy simultaneously or 3 3-gallon carboys.

I'm using a ceramic reptile heater as my heat source and obviously the freezer as my cooling source. I have a fan to keep the air inside moving. I'm testing and calbrating everything now. I want to do my first brew in it next weekend.

I've never used a fermentation chamber before. Anyone have any tips or tricks?

Some things I've been thinking about are:

The thermostat is free hanging. I've seen people put them in water, or at least enclose them. I know others use a thermowell. Is that something I should think about?

How do I account for the heat from fermentation. Since I do not have a thermowell I'm assuming I should set the fermentation chamber temp lower than my target tempurature for a few days. Any advice?

Any thing else I need to think about?

Appreciate the help.

I have a similar setup, with the temperature probe free hanging. I use the stick-on theremometers on the fermentor and adjust the temp controller regularly throughout fermentation to keep it where I want it. I would think that using a thermowell would allow a more hands free approach, but I don't mind an excuse to peek.

A lot of people will tape the probe to the side of the fermentation vessel and insulate it from the outside air using some bubble wrap or something else.