In the current configuration, when in PTO mode, two motors are on the drive train and one is on the PTO, but it could be inverted easily. Since the PTO motor is not connected to the drive train when the PTO is engaged, it can be driven separately. When in the full drive train mode, all three motors are on the drive train.
The weight is slightly over 12 lbs with materials set correctly according to Inventor.
Here's a link to the CAD:
https://workbench.grabcad.com/workbe...GLc2OPK4aS5nCL I haven't used GrabCAD partner spaces before, so let me know if it doesn't work.