The changes you need to include (to convert to rail buttons, or eye screws) are really pretty simple. You need to add some fitted blocks of tough wood in a couple corners, tucked against the inside wall of the outer body tube and against a centering ring. You need to fit the blocks against the curve of the body tube and glue solidly in place. You will do this in at least two places, forward and aft, where you would otherwise put your launch lugs. I recommend you start with a 1 inch square of 1/4 inch thick plywood, with the wide face of the block shaped to fit against the body tube. You could get by with a slightly smaller block (3/4 x 3/4?) if you can remember where you put them, so you can still drill thru the middle of the block.
The most tricky part of doing this is remembering exactly where you put the reinforcements so you can later drill a pilot hole thru the middle to mount the buttons. And be sure to line up your reinforcements at the same radial location, so the buttons also line up.

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NAR 20602
used to be "powderburner" in another life