I've been looking at a lot of pictures and videos on this but wanted a discussion to go along with that to further my understanding of other's perspectives/solutions to this.

Welcome that idea but just checked, zero anywhere near me.

Unfortunately it’s not that hilly and that design wouldn’t work for my set up, but I appreciate the suggestion.

That would be perfect, but so far I’ve whiffed on finding one. Gonna look into a few of the sourcing suggestion that others made though. I even have a huge lumber yard near me that said ‘we do not have that product’ when I asked for the 12” pole. Not sure I believe that.

My chosen system has a spring break. What is stronger I wonder: 4 to 6 ea of 2x12s thin side facing the termination point with the line wrapped around them like in the video another guy posted here, or two 6x6s in line with the line through them. Hmm

Honestly, this is the solution I was hoping someone would suggest. I might up that to 6 of them. How did you deal with cable pinching when running it around something square?

very informative answer

Oh yea, I would wood glue them together and then look for some kind of bolt to run through them to connect them all together, or an appropriate tie/mend plate or strong tie product I guess.

What about 4 6x6s and run the line around them instead of through a single 6x6?

What do you think about 4 6x6s glued and screwed together with the edges sanded round so as to not pinch the cable wrapped around them...

Appreciate this. I can adjust the drop with placement on the tree and the eventual termination platform. I'm just guessing at the drop right now anyway but will make proper calculations prior to eventual construction.

The start point doesn't need to be any higher so that doesn't need a landing platform (I'm in hill country so have plenty of fall already). I did plan to build a platform at the termination point though, but that has a tree so platform infrastructure doesn't give me anything I do not already have. Its the origination point that is tree-less.

So would you drill a hole at say 7ft above the ground on the 6x6, run the wire through it and then anchor it a block of concrete on the ground? If it comes to that I guess I can go that direction but the presence of a wire going from the post to the ground with kids running around creates a possible injury risk.

Can't drag it on the road that way :(

Zero trees in the vicinity of the start area. I do have a playset but there are warnings about not connecting it to playsets as they are not usually sturdy enough. All the vertical posts on that are 4x4s and I'd bet they'd snap under the load. I don't really want to build a big structure, just looking to try and comply with the load requirements with a vertical substitute for the 12" diameter post.

Not that I'm aware of. I also do not have a vehicle or flatbed big enough to transport something so large so getting someone to have, let alone deliver, said post is not going anywhere. I'll look into the steel post idea.