Yeah, I'd make sure that feet don't contact the ground. Not exactly the same, but I have a Bikes at Work trailer for my bicycle. If I push off with my left foot, it's very easy to not stop the push-off in time and get my heel caught between the ground and the trailer hitch. This can be very painful especially when the trailer is loaded. Needless to say, there is no give. I'm willing to bet that a loaded quadricycle would be just as heavy and unforgiving.