A larger line would have been the answer. At 525 feet, 1½" schedule 40 PVC or PE would be adequate. PEX might need to be 2". At this point, storage is really the answer. You mentioned a hill. Keep in mind that each 10 feet of elevation change causes pressure loss of 4.4 PSI. If it is a tall hill, that also has to be factored in.
Yeah, I can see now I should have gone with a larger pipe, and the cost difference between 1'' pex and 2'' pex was not huge. But digging up my road (I sleaved the pex line in 2'' PVC to protect it) and replacing all of that would be costly and time consuming. I think I would rather donate a kidney than to do that again.
The only other thing I can think of is that I bought the pex in 250 foot roles, so there are three unions on the run. Also, As I think back, the one area that might be a possible "kink" is where I brought the line up to go into my crawl space. I burried the line at over 3 feet deep (I'm in TN, where inspector told me 18'' is deep enough), then when I got to the house, brought the line up and then into the foundation. So the pipe does bend twice to go up into the house. I put 45 degree pvc corners over the pex to protect it for both bends. So unless the PVC has crushed (I doubt it), I don't think the line is kinked. But I did have to work pretty hard (it was cold outside at the time) to get the 1'' pex into the 2 '' pvc 45 degree turns at the end of the run.