Using the search, I see where a few have used this method for small boats but how about with a larger boat like a ~7600lb 29' Fountain? Lift is a 10K lb asymmetrical Bendpak.
Where would one find the center of gravity for the same boat w/twin big blocks? How long could it stay on the lift before the hull starts changing shape?

Center of gravity, in general, is one third the way up the hull or about right at the bulkhead behind rear bench seat. If the lift had locking arms i dont see why it wouldnt work and as long as you were well within the weight range. I assume you are very familiar with whatever lift you have? Its one of those thing where your on your own and not likely going to find a lot of guys that have done it. Use your head and be careful/pay attention. . . . . (disclaimer this does not endorse or verify that this is even possible )

this translates to......its not my boat so go a head......lol

It could sit for a while because you need to block it like they do at marinas when boats are on land. Support it on the keel and use the arms to balance it.

If it were mine, I'd firmly affix long 4x4s across the arms/pads, and make a "bunk" out of them, and lift it up that way. Remove the trailer, and ease it back down to some concrete blocks topped with wood/carpet to support the transom and keel; but also have the arms still supporting the boat as well. Lift it only 2-3" off the trailer, and pull the trailer out slowly, and only a couple feet, immediately placing the blocks at the transom, and have the keel block setup ready to go. Don't pull the trailer out completely until the keel block is in. This way if there is any slip, fall, or failure, the boat is still going to land on the trailer.

Good replies all around, Thx guys.
The lift arms are rated at 2500 lbs each so getting the arms positioned correctly WRT the center of gravity is going to be crucial.
I like the bunks idea with a 4x4 (covered with carpet). That would also help prevent the arms from trying to move around independently. The arms lock but there is some movement with the locks engaged. The further the arms are extended, the more pronounced the slop in the locking mechanism becomes.

I measured the boat width and compared to the distance between the lit posts. Plenty of room there. Then I noticed there's an excursion at the bottom of the posts where the lift arms connect. Measured width from outside edge of the tires and my clearance dropped to less than 2". Looks like it will fit but it will be a PITA to get the trailer positioned correctly.

There's a lip at the bottom of the gunwale where it goes from vertical to horizontal for abt 4" then goes downwards again at an angle. This 4" horizontal portion is where I envision the lifting would occur.
Is this a good place to lift from? I'm concerned that would tend to push the top of the gunwales inward. If there was a bulkhead there it would probably be OK but if closer to in between front and back seats, that worries me. Cracking the windshield has also crossed my mind.