Encapsulation/bonding Ti-6Al-4V internal chainplates

[Brion Toss]

Hi,
It looks like no one else wants to step up to this, so I'll offer an utterly unqualified opinion. While you might find that some mix of materials would indeed prove strongest in this application, it is very likely that just about anything remotely appropriate would work; given sufficient surface area to distribute load, and adequate adhesion to the original material, it would seem easy to create a structure that would be much stronger than the standing rigging.
I am delighted to hear that you are using titanium, since, as I'm sure you know, it is not vulnerable to the crevice corrosion that probably ate your original chainplates. One thing to consider doing would be to leave drainage, so that any moisture, whether intruding from above, or from condensation, wouldn't hang out in the "pocket," not because I'm worried about the metal, but because the 'glass won't discolor, and you'll still be able to see if anything is leaking, before it gets serious.
Fair leads,
Brion Toss