Probably the 42" because that will put the trailer a little farther from the camper. This might become very important in a tight turn, or say you are leaving a gas station, and the truck front axle is in the middle of the road, about 1' higher elevation than the rear axle, so the camper is leaning back. Now the trailer tires are still up on the curb, above the street water channel, and say 12" above the rear axle tires. This puts the front of the trailer at a downward slope, and closer to the camper. To close, and you have the trailer trying to get into the camper, and that can not be good.
I saw the trailer trying to get into a motorhome in San Diego a few years back. I think it managed to get just a little under the skin of the motorhome, but am SURE that it made contact with the motorhome rear wall. I was watching them come out of the gas station, heading straight into the street, like trying to make a left turn, but actually going to the right. I have no idea why they pointed the RV so straight out to the center of the roadway, but at the last second started to turn to the right. It was a 3 lane street (each way) and the curb gutter would have been about 8" lower than the center of the roadway, with the gas station where the trailer tires are would have been about 12 - 15" higher than the motorhome rear axle tires. Bamm! That's gotta hurt. . .
Good luck with your travels, and take it easy leaving a gas station, take it at an angle, not trying to make a left turn when leaving the station if the angle is steep. If only one rear tire was in the ditch section of the roadway at a time, then the trailer would not have hit the back of the RV.
Fred.
Money can't buy happiness but somehow it's more comfortable to cry in a
Porsche or Country Coach!
If there's a WILL, I want to be in it!
I havn't been everywhere, but it's on my list.
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