16' deck trailer for reference, although both my L3200 & that trailer are gone a couple years ago. Don't remember if the 16' included the ramplets at the end. All the economy 2 & 3 thousand Ls are the same size.
You need a 18' minimum trailer, preferably 20 or 22'. I got lucky with the super long tongue letting me hang the loader off the deck to fit & ballance the machine.
It's going to be the same as the L3200, L3800, L3301, and L3901, so don't limit yourself to just asking for the 2501 dimensions. If I remember tomorrow I will measure my L3200 out in the barn.
I went out and measured my L2501. It has the LA525 loader. From the tip of the bucket to the tail of the three point is 154 inches, or 12 feet 10 inches. This is not the quick attach bucket. I suspect that option would increase the length slightly.