Keystone uses something similar on their SRX model.
The floor height and door height are about the same on your Coleman as the larger toy haulers that have a dovetail. If your garage decking is level all the way to the rear, I think the double ramp compensates for the drop a dove tail creates???
Mike & Helen
2014 Voltage 3895 EPIC III
2013 Ford F350 CC DRW FX4