As far as tunneling under stuff, prior posts re. the larger (than your intended water pipe) schedule 80 PVC and a pressure washer work fairly fast. I gave up on a "steerable" Vermeer trencher - bear to trench straight on irregular ground, and slow, and susceptible to larger tree roots (keep a shovel and hatchet with you). So, being in the South and only needing 1-1.5 feet, I used a subsoiler on my tractor (about 4 inches wide, about 2 foot soil penetration on my unit), and when pulled behind a reasonable sized tractor will tear up most roots and allow are very straight trench. I widened the trench with a potato plow (only feasible once tough stuff zapped by subsoiler) - and voila, a trench about 1.5 feet deep, about 10 inches wide, straight as an arrow for 1000 yards, and in less than 1 hour of tractor time. The soil has to be relatively firm - sandy stuff would probably fall back into the trench. This, of course, was learned from others on this forum - I'd have never thought of it. I laid 20' lenghs of PVC, and wrapped all stuff coming to the surface with rubber foam insulation beginning at the junction with the water line 1.5 feet deep. Filling the trench, so it won't settle later is always a major pain, and takes loads of time (and dirt). Used FEL to push dirt back into the trench, then dumped fresh dirt every 50' or so along the trench, box bladed it flat over the trench, drove the tractor the length of the trench (with 1 set of wheels tamping down the dirt), repeated the dumping dirt and box blading 3 more times - by then driving the length of the trench with a tractor loaded with box blade and FEL had no effect on tamping dirt - we'll see if such holds up over time. Is there any plow type of attachment that will achieve the depths needed for you Northern folks?
P.S. - if you ever need to run electrical line alone, a subsoiler is the ticket - and some rig a hollow tube behind their subsoiler and are able to lay electrical line and flexible waterpipe simultaneously - I seen one such set-up, old and rusty, in a local farmer's yard, and he swears it worked over a distance of 1/2 mile to his cabin in the woods, but I've never seen such a set-up in action.