The best you'll get from a traditional lifter (chas' is actually a shelf) is the cover folded in half, standing up on the ground next to the spa.
Yup that's the idea . . .
In terms of clearances, they're described as "rear clearance", which is the side of the spa the cover opens to, and "side clearance", which referrs to the sides of the spa the lifter is attached to.
There's plenty of side clearance - 18 inches or so, what's tight is the rear clearance, as the cover will need to go vertically down the cabinet without scraping. Once it's vertical, it should be fine, it's just that moment, the "tipping point" if you will, where it is going from horizontal to vertical. The most I'll get, even shifting the tub a bit, will be about 15 inches of room.
Also, seems like the best way to go will be to slide it down in front of the equipment panel.
I'll see if I can get some pix together . . . when I was last at the dealer, they showed me a lifter that seemed like it work - they said it needed 12" clearance - not sure of the brand but it was a Sundance/Jacuzzi shop.
Thanks for the response!