I've GPS'd the major trails from Presque Isle to Van Buren and some of the links inbetween for my job and our ATV enforcement unit.
Since you're a beginner then I would say the Newport to Dover trail would be perfect for you . . . there are actually some nice views in places (i.e. beside the lake in Newport) and thanks to Menace66's caches you will stop in some places that I never noticed before while cruising by on the ATV . . . definitely take the time to stop and check out his caches and views. As I said once you get past the Irvings in Dover (you have to drive over an old -- and high -- railroad bridge to get there -- but fear not as it is now well planked and has railings -- something it didn't have when I first rode this trail) you want to go behind Irvings and follow the trail until you reach the T-intersection . . . I would then recommend going right and heading down the trail to the Bear's Den for a nice lunch. A word of caution . . . while this trail is flat there may be wash-outs, bumps, potholes, etc. and at the start of the trail and in Dexter there are lots of road crossings so just exercise some caution.
In answer to your question . . . yes . . . you can ride two-up on a one-person ATV . . . it just throws the weight balance off a bit. Usually this isn't a real issue as long as you get used to the extra weight and compensate for it with regard to breaking, navigating uneven terrain, etc. I would assume you also have a back seat/compartment attached to the ATV since your rider would find riding on the hard plastic or little bit of the seat behind you quite hard . . . if so make sure the seat/compartment is secured well to the ATV. Some folks also add foot pegs to this seat/compartment for added comfort for the rider if they're short-legged.
. . . As Hiram mentioned he has plans in the works . . . I think he's tentatively calling the event "Tread Lightly 2009: I'm Calling Shotgun" and he was talking about hosting it in the Machias area possibly.
For anyone interested this event is really a lot of fun . . . the trails we go on are not so technical that you need a real rock crawler and loads of experience . . . but we do leave the tar and occasionally need to use the 4WD. For those without 4WD never fear . . . there's always plenty of room in the vehicles . . . and this is always a great way to nab some of those caches off the beaten path that would either require a long hike in or beat up a car's oil pan. Plus there's the added bonus of camping . . . and seeing me at an event. ;):D
I'll never forget my first riding experience in the County. Met up with a guy I met on-line from Washburn -- Roger Hewitt (aka Chief Wiggim.) Rog brought us up the RR line one day to Van Buren . . . when he turned on to the sidewalk I thought for sure he was going to get us in trouble . . . especially when a police officer drove by . . . but then the police officer just waved to us . . . such a different experience . . . such a nice experience. The next day we went down to Mapleton and the trails at Squa Pan. On other trips we have rode to Mars Hill and then further down to have lunch at the Blue Moose . . . trailered up to St. Agatha and rode to Fort Kent . . . can't say as though I've ever ridden on a bad trail in the County . . . in any season -- winter or summer.
Dave and Gail still ride. We have gone on some real nice rides the pst few weeks. They have been super busy with the house renovations and they have family here from PEI for the week.
I was thinking of heading up to the county somewhere on an atv ride but it would only be a day trip. If it was going to be just a day trip leaving from Bangor area, does anyone have any suggestions?