Understand this
Even if you stand on the roof on one foot
That foot is spreading your weight over complete area of your foot that's a number of Sq inches and not just one or two bolts and it's pushing down from the top where it has to push through the roof not pull out from holes pulling down, like lag screws from inside
And you cannot stand on your roof on one foot for hours at a time. Like you can sit in that yoga swing, the forces involved are just not the same no matter how you try to rationalize it
Can you mount the swing..Yes
Is it safe... No ..not unless you put a plate on the roof and drill holes and run bolts thru the plate , spread the force across the top of the roof
a few lag screws inside the ceiling into a (2) inch truss will not stay, they will pull out, or pull down a section of ceiling and roof
You are owning it, you are not worried about resale, be safe do it correctly
