The apartments I used to live in had the same policy (no working on cars in the parking lot) but I did it any way and no one ever said anything. That is where I did all the mods to my car with the exception of the things that had to be welded in. I kept it looking very clean and not a lot of parts lying around and never left it on jack stands. If it doesn't look like it is being worked on when you are not there maybe they will not say anything.
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James Cox
nochevy@hotmail.com
1991 Mustang LX
Best 1/8 time on motor 7.686 @90.20mph