Agree fully with those suggesting you carefully reconsider that 10" drop. Thought we needed a serious drop. Bought one that seemed to make the tow bar level....when the coach was empty. Then loaded it up for a trip and the tow bar was actually a bit lower at the coach end when everything was said and done.
Still within limits but lower than it probably should have been. Went on the trip and didn't have a problem until the last fuel stop.
Bottomed out the tow assembly transitioning from the gas station to the road. Have since purchased a drop that is 2" less and so far everything seems fine with almost no perceptible slope to the tow bar between the toad and the coach. And less chance to bottom out.