Point taken.
However, this topic is better suited to a forum on more advanced vehicle topics than just ebikes, but here are some suggestions:
First and foremost, keep it simple.
- only go to a hybrid drive if it is absolutely necessary - with a trailer there is a lot of additional space for batteries and keeping it all electric reduces complexity considerably.
- if a hybrid is necessary, use a series hybrid rather than a series-parallel
- it is questionable if adding dual drive capability adds reliability - it certainly complexity to the finished system and adds design requirements that are far from trivial
- consider repairability along with reliability - use more common COTS equipment that can be quickly swapped out as LRUs rather than making "snowflakes"
- to address commutation timing for two motors there are two practical choices:
- lock the two motors together with the correct timing, or
- use two controllers
- consider that this sort of vehicle probably requires considerable low speed torque for the weight carried and terrain - the drive system should be selected accordingly
- look at the simulator at ebikes.ca to get a better idea what motor, wheel size and voltage may work better in this application