Might check further on advisability of using PEX underground. I put in 900' of water line some years ago, most of it paid for by the government as part of a soil conservation and livestock program. I hired a plumber to lay the line and make the connections. He really wanted to use PEX. The people in charge of the program would not permit PEX but they didn't say why. PVC was acceptable and recommended. This was direct burial if that makes a difference - maybe PEX in PVC might have been ok.
Off the subject of water but on the topic of trenches, I just dug a 650' trench down the horse pasture to replace a failed direct-burial aluminum electrical power line - I used THWN copper in conduit this time. Took me a couple of days but all is connected and working. Twas a good test of my new toy, er, farm machine. Waiting on a few dry days to fill the last of the trench.
Attachment 420596
JKJ