The 24+1 option is really great. Just make sure you leave something in the front that can distract anyone who gains access.

It would be annoying if you wrote down the 24 and forgot the 1, but it's a risk I'm willing to take. I can also write down my seed phrase in an encoded zip file or something like keeppass, but then again, I could forget that code, so best to keep the last word somewhere easy to find as well, but separate.

I'm wondering what you mean by a touch insecure? Sure someone can take it from you, but the idea is just to make it more durable. If you encrypt the words, leave one out, randomize them, etc. You risk forgetting how it is done. Perhaps you can save that info in the location you save the +1 word. I guess if you can just memorize the list, it would be really secure, but you still aren't safe from someone threatening you.
As far as durability, I've read that titanium rods would be better, but they are tougher to engrave on than a flat surface and a little expensive. Also the surface with the words would be exposed to abrasion. Stainless steel plates or tiatanium plates would be better than zinc coated, but all three are going to last quite some time unless stored in a really poor location. I think securing the plates together with bolts may be a touch better, but unnecessary. Also, if someone gets in they can just screw it back together. With ties, they will need new ones. Perhaps putting on a seal so you know if someone opened it would be best.