Based on the specs of the Lectric XP 3.0 and the fact that you'll be installing this on flat towed vehicle I have to recommend the Yakima OnRamp Bike Rack for 2 Electric Bikes # Y36FR. It has a 66lb per bike capacity to accommodate your 57lb bikes (never haul the bikes with the batteries installed, they should always be stored inside of the vehicle). The trays accommodate up to 3.25" wide tires so they'll work with your 3" wide tires. The padded clamps can easily adjust around to grip the... view full answer...
No, they are not! The locking casters that are included with the Hollywood Racks Rack Valet Rolling Storage Cart for Hitch-Mounted Bike Racks item # HRRV-1 aren't going to work very well in grass. They're designed for hard surfaces. It will be pretty easy to swap them out for larger casters/wheels that will work in the grass.
I have linked the instructions below so you can take a look at how this rack is assembled. view full answer...
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