Are you on Kiwi time Phil? Any earlier and you'd be up before you went to bed!
Yes what you say makes perfect sense, and I have some dimensions from commercial units saved for that reason. Which I can post if people want. But I was more interested in assessing the option of using my shed frame.
If I went to the maker of my shed and asked how much can I lift I suspect the answer would be 'Zero. It's not designed for lifting, it's designed to keep the rain off.' If we take that at face value, the question then becomes, 'How can I modify my existing structure to make it more lift-worthy, and how do I quantify (estimate) the Safe Working Limit?'
If you want to talk to me, please click my name and send an email. I'm not here much and PMs can go unnoticed for months.