How fast do you want to go, and what is the total load (trike incl batts and riders)? What kind of terrain for tandem riding? Are you essentially talking about something like a T-rex, but electric. If so, then I'd question using any single hubmotor. The one LFP mentioned may be up to the task in terms of torque, but I'd want to see no-load current at high rpm to see if the core design is good enough. eg I have a 273x50mm motor that I've run at 30kw peak input with a light load, but on the highway above 60mph or so the motor ran fairly warm, so it can't come close the the 107mph I've hit with my HubMonster, but it would be unwise to set HubMonster up for that kind of speed pushing a 2 person load. Sure it would be fine on flat road with those aerodynamics, but with electrics the fun is in eye popping acceleration, not just a straight line speed run.
Another consideration is that other than those made for cars, ATVs, etc., hubmotors aren't designed for big side loads, so if you're talking about something to haul ass through the twisties, then the trike needs to be a leaner to use a hubbie designed for a two-wheeler.