My energizer is in the barn and I have run insulated electric fence cable (mostly buried shallowly) out to the pasture fence. As long as you don't crack the insulation when burying it, it works well.
Last year I set up a small, remote paddock with battery-powered energizer and solar array charger. Sadly, somebody stole everything but the ground rod and the paddock fence itself! This at the same time all the hitch pins from my parked implements, plus my wood
chipper PTO shaft disappeared.
An expensive solar array fence energizer would be the best solution (IMHO) for your situation, but it might also be a big temptation for thievery, especially if it is left at an unattended site for long periods.