Ok, since everybody jumped in to help I guess I'll post what I know.
Width of the Avalanche is 8', and the distance from the kingpin to the inside corner where impact with the truck would be is exactly half, 48".
In a 2014 F250 crew cab (and other years) the axle is 36" behind the cab, so that is where the B&W will be mounted.
If you take a tape measure, and put it in the center of the ball and roll out 48", you can get your rough angle pretty easily when you rotate around the ball towards the cab. Somewhere near 55 degrees to my estimation.
After doing extensive research, I've decided to go with the Andersen Ultimate (
) for a few reasons:
1. Lightweight (35ish pounds)
2. Easy to connect and disconnect on uneven ground
3. Doesn't cause unnatural stress on the RV frame
4. Configures to give me as much as 9" further back.
5. Supports an offset ball for the B&W receiver that would give me another 4"
6. Multiple height adjustments to account for pinbox/kingpin approach angle to truck bed wall clearance.
7. Cost is about $700.
A comparable slider is going to cost more, and I'll not be able to remove it from the bed of my truck on my own. They are a couple hundred pounds or more. They don't hitch/unhitch well on uneven ground. What is more, is that most sliders give you 10" of rear travel - while the companion slider gives you 12". I can get as much as 13" with the Andersen if my truck bed/tailgate will support it.
Good luck to anybody looking for help in the future.