Coach, when you're under there, get the part number off of the white sticker on the oil pan and call Cat to see how much oil your engine should hold. I understand Cat put three different oil pans on the C7 and most MHs use the shallowest one, but it usually has the deep oil pan dip stick. If you take your MH in for oil changes they most likely overfilled it. You need to put the correct amount of oil in and then put a new line on the dip stick.
Having said that, since the breather tube usually comes out on the right rear of the MH, I don't think that's your problem causing oil all over the bottom of the engine, though it could be putting an oil film on your intercooler and radiator.
Let us know what you find.
Nodwell RN110 out moose hunting. 4-53 Detroit, Clark 5 spd, 40" wide tracks, 10:00x20 tires, 16,000# capacity, 22,000# weight. You know the mud is getting deep when it's coming in the doors.