I agree with the 4-way. We've had both 2 and 4 way. With the 2-way there will be times you'll have to put boards under at least the rear wheel of the truck to get the hitch to release because the truck and fiver are on different planes by more than an inch or two. Then, of course, that board under the truck wheel gets moved before you are ready to hitch up again and you can have a devil of a time getting the board in the right place. You think you have the hitched lined up with the pin, then back up on that board and the pin is no longer centered with the hitch (truck moved in an arc). So bring it off the board, move the board, etc. With a 4-way you may still have to do that but not until the difference if four or five inches. Much more rare.
As for 15k or 16k, the 15k is plenty. That's what we use. But I'd go for the 16k so if you ever trade FW's you have a bit more breathing room. And for $200 I'd definitely go 4-way.
All just my opinion.
Here's a situation where we also had to put boards under the truck wheel despite the 4-way. Hitching up was NOT fun!
