Years ago, when I was a 2P, I asked for 1P status based on my booked itineraries, and UA granted me a "once in a lifetime" exception. So, YMMV.

For reference, I was living in Japan at the time, and was hovering around 45k EQMs; the return flight would have put me at 1P. I wanted 1P beforehand so I could take of advantage of the *G benefits. It paid off handsomely, because I got *G lounge access, the extra bag allowance, and an op-up on the return flight!