You're looking for a scissor clamp. They use them in film and video production all the time. They clamp onto the rail between the ceiling tiles.
You'll want to look above the ceiling and make sure you grab onto the frame somewhere near one of the wires holding the ceiling up.
https://www.amazon.com/Impact-Ceiling-Scissor-Clamp-Support/dp/B07994FRY3
Great Working Tools Kayak Hoist... https://www.amazon.com/dp/B07WDR7ZDF?ref=ppx_pop_mob_ap_share
I used this an have been very happy with it. I don’t think it would be hard to reproduce if you have a few spare parts.
Is your ferrule made for 3/16" cable or 1/4"? I have had some problems with cracking when using an oversized ferrule. Also, I'm not sure what you're using to crimp but you'll get better results using the right tool.
I can't answer your question.
But, a very nice resource is the book "On Rope" by Smith and Padgett. It has more than you ever thought you'd know about rigging, from climbing to arbor to other niches. It's focused on caving, but not really.
https://www.amazon.com/Rope-American-Vertical-Techniques-Rappellers/dp/1879961059
Circling back, they have a section on sewing, specifically commercial vs homemade that can answer your question.