Theoretically you could scratch in a 13/16 - 16 UN-2G thread and utilize the tubing bore as your minor diameter within tolerance. That would only leave you with 0.044 inch wall, so it depends on what thread performance you would require for your design.
In your position, I would probably re-write my own thread form and base it off a Stub Acme geometry. Noting you only have 0.075 inch wall, I would make the minor diameter of the Box equal to the tubing ID minimum and go for a 1/32 inch thread height. That would put you at least even with the UN configuration above, but the Stub Acme geometry is a much more robust thread. So you would recover somewhat on strength. The equations for the Stub Acme thread can be found in the Machinist Handbook, but I would probably go with the ANSI standard so that I could pick up the miscellaneous threading information for the complete case. You could make the Pin the gauge for the Box and have QC/QA do a three wire measure on the male threads for some sort of machining control. Again, not sure of your application so the thin wall may be an issue. For machining the Box, I would wrap the OD in surgical tubing to limit the vibration during cutting of the major thread diameter. This is just an old machinist trick.
The only other thing I can dream up is talk to a watch maker, if you can find one these days. They're pretty sharp cookies with miniture parts, doing a web search may ferrit out more information.
Pretty tough problem, mechanically speaking. Good luck with it.