The rear forks of an ICE trike are asymmetrical.
With a nine speed cassette on the back hub, the wheel has no dish.
This means that with an IHG hub, the wheel will have to be built asymmetrical with a reverse dish.
That's how my Rohloff wheel was built.
Downside of a symmetrical back wheel .........
Tyre wear ?? may be increased. Tyre size ?? may not be able to fit the fattest tyres (50-406) without rubbing frame. Refit after puncture ?? you may not be 100% square in back forks, making it slightly harder.