They look workable. Is the middle section of each adapter necessary? What do they weigh?
The couplers are loose enough that I'm using small pieces of tape on the exterior body to hold the stages together until separation.Just make sure the staging couplers are not too tight, and you'll be fine.
See post #15 in this thread from some guy named John Boren.
Good luck!Many years ago I was playing around with CHAD staffing and came up with the following design. The rocket a ESTES Patriot was redesigned to accept 3 motors internally without a separate booster section. You would tape the 3 motors together and slide them into the rocket motor mount. which was...www.rocketryforum.com