I thought about using something like this myself a few days ago, but more for reinforcement with a standard coupler so both sides of airframe are squeezed. Double shear for any pins used? Mainly for short inner couplers / not much room inside for laundry.
Only tangentially related: mailing tubes seem to be measured by ID instead of OD. I've tested w/ 2" & 2.5" vs Estes PSII, makes a good external cardboard coupler.