....wondering how much stretch there actually are on these.

Yep. Love it. It has a little stretch to get a good snug fit but you have to really pull on it to stretch it. It won't stretch from the rods while boating if that is your concern. I trust mine holding my rods on the deck while trailering to the lake. It feels like a heavy rubber and seems to be pretty durable from my use so far.

Well my main concern was the sizes they come in....I'm right in between both that are offered and told there was much stretch at all so it may be an issue.

Had to go look at mine. One of those items you install but don't really pay attention to afterwards. Mine looks to be about 12" long and it does have more stretch than I thought. I'd estimate about 3" of stretch.

Hope that helps

I made mine...Cheaper, more color choices on bungee and pretty damn easy to source the parts (Amazon)

They work well, but you will need to replace every year or two, depending on how you store your boat

Buy the next longer size.
You can take the end off and cut them to size and put the end back on.
I just did mine last week. They work great.