I have experience running Mac mini’s 24/7 in exhibitions, inside a table top. Never had any issues with temperature. The exhibition spaces are often not air conditioned, the warmest has been a show in a temporary event tent setup in Abu Dhabi UAE.
The current Mac Mini lists these Operating and Storage temperatures:
Operating temperature: 50° to 95° F (10° to 35° C)
Storage temperature: –40° to 116° F (–40° to 47° C)
Relative humidity: 5% to 90% noncondensing
A quick look at a 2017 Macbook lists the same OT only ST is -20C instead of -40, maybe due to the batteries in a laptop? You might want to look up the specific OT & ST for your model but I’m pretty sure it’s in the same ballpark.
So 75-80F should be within the OT. And with those light workloads I wouldn’t be worried. There are also safety measures in place where the computer will shutdown when overheating. You can also install iStats to monitor the internal temperatures of the components if you want ease of mind.