I did this in northern Indiana for 5 years… 3 125 gal tanks and one 180 gal. I had a 30k btu gas heater to keep it ambiently warm in winter and used fans in summer. Summer was harder!
No issues with “fumes”. Unless you’re running the car with garage closed this is a non issue. I have a family of 6, two vehicles (both V8) were parked in garage with tanks in 3rd bay. We were in and out plenty. I have the full array of Hannas and never saw anything unusual.
You can do it. Just have to pay attention to temps.
We have since moved and I have these all setup in an unfinished area of basement… all still running and without any real change in “behavior” from a system perspective.