I own a 2006 PR147 inline and trailer three sleds on a semi-regular basis. I will post pics next time to show them in place. Here is a brief description.
Drive 1st sled in from rear on pass side just far enough in to clear rear bumper. Back the second sled in from rear next to 1st sled. Drive third sled in from front ramp right behind the second sled. The rear bumper of third sled will slide right into V of tailer with 6in to spare. If you need a little extra room, you can put a section of 6x6 under the track of second sled to raise rear bumper for third sled to drive under. Works the nuts, but you will not believe they will fit until to try it! I have trailered two revs and one F7, two revs and one yamaha srx., Two rev xp and F7, two rev xp and yamaha nytro.. one nytro, one F8, one rev....all have fit the same way. The trailer is rated for 5500lbs and its weight is under 1700lbs

Please post track length of all 3 sleds.

They are all short tracks 121in

Thanks, that's what I thought.

backing in must be a pain in the arss

Better to have the option of three sleds than not...not difficult at all.