If these things are well constructed, they should be built to withstand extremes. A vehicle environment is not an easy environment to be in. If it can't hack the extremes, then the quality isn't there.
I kept my DashDAQ (Spartan tuning) in there 24/7/365 without any issues for several years
Now if you are worried about theft or something a long those lines, then that would be something else entirely.
2014 6.7 PSD King Ranch F350 SRW