My cab is 12', I have set back axle, (not sure what my cut angle is) my box is 28' so overall I am exactly 40', my wheel base is 336". The first 6 months where somewhat tricky getting use to the length and turning radius. Now I know where I can go and where I better look for a better way to go. Throw my 20'(24' overall) trailer on the back and tight secondary cross road turns can be interesting, but general traveling is no problem. Wouldn't think about pulling the trailer to most of the campgrounds we visit around here. These are definitely not day trip vehicles.
If you are looking at classic FL's, Pete's & Kdubs your turning radius will be worse. With that out front axle and long nose & longer box you will need even more room to make your turn. You just have to determine how and where your going to use your rig. If it is to the track and back, you won't have a issue. Looking to get on the back roads and do some site seeing with stops at road side attractions, good luck.
2012 Showhauler 28'6" Motorhome on a Columbia w/ 450 Mercedes.