I think it works better from the inside.
I'm using the washer and ally tube to gauge the length I need to make a single tube/spacer.
Got to try and work out how to stop the spacer falling past the latch or how to attach it to the spring.
I got three stainless steel mechanisms from Chinaland for about thrupence on ebay and they come with the small lanyard attached with an eyelet at the other end.

https://www.ebay.co.uk/itm/3pc-Quick-Release-Spring-Pins-Stainless-Steel-w-Lanyard-for-Boat-Bimini-Top/302496432352?hash=item466e3140e0:g:KdsAAOSwG49cJJXC
Gus