Near Carlisle... West of Harrisburg.
I thought that I recognized the name, but the guy I'm thinking of is from Berks County, I think.
You mentioned having some big logs, and were questioning the wisdom of the 48" Alaskan. Granberg mentions that a smaller mill is much more handy on smaller logs than a bigger mill. Keep in mind that a square cant will be up to 70% diameter of the small end of your log. This in mind, a true 50" log will yield a 35" cant, which is wider than a 36" mill is capable of. At best the 36" mill will cut 33.5" width, and you had better have a big saw with 40"+ bar to achieve that. When the log/mill/and bar become very large, its time for the "helper handle" on the end of the bar at a minimum. I've seen video of big logs being cut and there were actually 2 power heads in use, one on each end of the bar.
If you make a top cut, drop the bar in the mill and make the bottom cut, you need only turn the log 90* once to make a square cant IF the log is less than the maximum cut width of the mill. If the log is larger, it can be turned multiple times, or else use one of the various "beam machines" or a mini mill to cut the sides to a useable width prior to making the bottom cut. Theoretically, this latter method wouldn't require turning the log at all, but I can't testify as to how square or parallel the sides will be.
As for rails on which to make at least the initial cut, I've used 2x4s, but other guys use lengths of aluminum extension ladders, while others buy the Granberg stuff.
My own Alaskan was purchased as the 24", and it will cut 21.5" width max. I've used it with a 272XP, but think my 066 will be faster. I may opt to buy either 30" or 36" rails for my mill to change as I see the need for, but can't imagine needing anything longer than the 36". I don't have an 088/MS880 or Husqvarna 3120, and really don't want to go to the expense for use once in a blue moon.