Lifting One Hull for Maintenance

[svcattales]

We don't have a big tidal range in Tampa Bay, Fl area so I can't dry out Cat Tales to do maintenance on sail drives and props. The saildrives/props need attention at least annually, but I'm trying to do haulouts every 2 or 3 years. I was thinking about lifting one hull out of the water at a time using lift bags. Has anyone experimented with this idea?

I found a company that specializes in lift bags for divers and salvage companies and they have bags with a 4400lb lift capacity with the right dimensions to snug up against my keels. I think I may be able to lift half my boat with 2 of these bags. If I tie the bags together (they have s/s tie rings) with heavy straps under the keel and secure them fore & aft with straps around the keel they shouldn't pop out, right? Is this a good idea, or great material for "Funny Home Videos?"

Another issue. Before inflation, the bags will extend up to waterline. As I inflate them, will I lose bouyancy as they start to rise out of the water? Will my 8800lb lift capacity be reduced to 4400lb when they are half out of the water? Isn't that what Archimedes would say? If I go for bigger bags, there will be more of the bags sticking out of the water so that might not work. Any ideas on best way to do this?