The 22AWG is less of a problem than the insulation material standing up to being buried in the ground. EveryDrop sells the right cable for $0.90/foot. You can buy it yourself, but most places just sell big spools of the stuff. I wouldn’t dismiss wireless so easily. Is the 75’ line of sight going through the house (then it’s not really LOS :-)? How many walls? You can always buy the new WL-1200, do the range test, and get at least most of your money back if it fails the range test. They will soon have the STX-100 which converts any wired meter to wireless and has a better antenna than the wireless meters. But it probably won’t be cheaper than a bunch of the good wire 
