"Bubbles" for your Ferrari

Unfortunately, my garage is a piece of junk. I keep my 308 and my brothers Lotus in it year round. After much renovation work to it, it is better, but alas, still junk.

Biggest problem now is that the floor has many cracks, and when it rains a lot, some of it seeps up, making the floor damp. For a long term storage facility, it obviously stinks from a humidity perspective (both cars are driven regularly). I thought about a pond liner, but my dad talked me out of it, feeling that I would soon have a swamp under the liner, and it would be of no use after some time with all the moisture trapped under it.

I guess the only solution now is the infamous bubble. I want to keep the cars dry. A garage rebuild is a few years away, as $$ permits. I'd rather spend the 30K it will cost me on my half of a boxer that my brother and I plan to together in the future.

Anyone use these things (bubble)?
Are they easy to get in and out of?
I drive my 308 on a regular basis from spring-fall. Does this seem like a viable option (the bubble)?

thoughts are appreciated.