Heat is not an issue. You may find your tent too cold if in a basement actually.
With the dimmer you can basically hang it as close as you like, although with greater distance you get more even coverage and less shadow effect.
Still messing with distance. I have a par meter so I’m using 500ish par for vege and 875ish for flower.
@bk78 some numbers a while back as well that I initially used and they work great.
I’d have to check my lights later with the meter. Just got the meter actually. I’m hanging my lights higher and letting the plants grow up to them. Sick of adjusting light height so using par meter and dimmer to make adjustments.
Last run I never exceeded 600watts on the fixture.