This is a hard shot. It's easier to throw high with either hyzer or anhyzer...lets you put some height on the disc while keeping the nose down much more easily. If you are throwing an uphill hyzer flip, you need something quite to very understable. Need to throw it nearly parallel with the line of the hill, let it flip up and maybe glide a little right. You aren't getting a full flight out of it anyways, so just don't go so understable that it will land on edge and roll.
The harder you can throw, the faster a disc you can use, and the higher above parallel to the hill you can throw a hyzer flip. If you throw too high or too fast/stable of a disc, it will stall out early.
With the anhyzer you can throw kind of up high over the apex of the shot, and it will start crashing into the hill eventually rather than meeting it at a softer angle like the parallel to hill hyzer flip. You'll throw the shot higher with an anhyzer, probably a pretty neutral disc in this case. I think this is a more predictable shot for where the shot will land on the hill, and you can throw it a bit higher without stalling it if you are decent at throwing annies.
It's tough though to throw these shots, it's basically throwing a distance line on flat ground, except now fairly parallel to the hill and much shorter the distance you would normally get.
Out of the discs that are in your sig list, the River/Thief are what I would be trying first as they are glidey, slow enough, somewhat understable, and still get good distance. I'm not as familiar with the Photon or Insanity. Plus you get so much distance loss throwing uphill, the consistency of the right disc stability is more important than a couple extra feet.