Is this a middle out compression situation?
I agree with qwksilver and g90ak.
If full length insertion is not a strict requirement it might be as simple as a quickshot connector or 3 and strapping in over the connected section.
One potential approach would be to design and 3d print a replacement end-cap for fleshlight cases which receives one case on each end, and also serves as strap location for the handy (if one has the appropriate magnets and a handy 2 it could probably be designed to include those as well).
Some thought to avoid the threads being weight-bearing is also necessary, or perhaps some reinforcement of the ring portions (cable ties or hose clamps come to mind) is probably necessary. I also am not sure if any of the handy devices are capable of moving that amount of mass.
How the handy is mounted or suspended (tripod? sawhorse? custom carpentry?) and how the cocks are positioned is then the complex part. If you have to account for large variances in D2F or angles far from horizontal… further engineering may be required.
This would also mean that one user always has an inverted experience of the script.
It would be possible to design a mount that accepts two sleeves and moves them in the same experienced direction at the same time provided both users are comfortable being very close to one-another (instead of moving a single sleeve as an I, it would move both in parallel, looking something like an H), but the mass/force requirements need to be considered.
A better outcome may be possible with a customized receiver design and a sufficiently powerful driving motor in an SSR1.