Would you think about extending the bottom longer below where the mounting strap sets?
If that was about 2 - 3 cm more you could accommodate this sleeve being used in an adapter for the OSR device in addition to the Handy. The adapter creates a Fleshlight mount that is used with any FL compatible stroker. See Here.
https://discuss.eroscripts.com/t/handy-measurements-needed-to-create-a-3d-printed-adapter/20900