Maintaining a low center of gravity is critical for proper leverage against the pull of your oponent. If you stand too tall, your strength will be ineffective due to being pulled off balance. Proper lean angle away from opposition not only allows you to brace your legs but leverage your upper torso and arms to maintain balance.
If the opposing team sways or whips the rope side to side in effort to knock you off balance, allow your arms to sway with the rope but do not try holding the rope close to your body (doing so will result in your losing balance). However, if your reach is good and timing is on, you can exaggerate your opponents side to side sway and use their momentum against them by furthering the sway just a bit further than they expect.
Depending on your teams unity, you can prepare your team for coordinated maneuvers such as slacking the line and surging. Shout a command to ready the line, then shout a command to abruptly slack (allow the line to travel back very quicly for a couple feet) in hopes of catching the opponent off guard and not ready for the slack. Immediately taut the line and take advantage of any slack afforded by the maneuver.
Surging regards coordinated pulling efforts by your team. If everyone isn't applying effort at the same time, your team mates could actually be pulling against your own team mates. Example, though the lead person is pulling in the same direction as the other team mates, if the lead person is just holding steady at the moment the person behind surges (pulls hard), the lead person is actually lessening the effect of the pull by the other team mates. That goes for anyone downline of the active surge point. So, coordinating a pull method can allow a smaller, lighter team to out maneuver a larger less organized team.
Regarding putting the largest person in the back (at the end of the line) - it is key that that person, even if they're the only one who applies proper leverage on center of gravity does so consistently. If the anchor stands up or holds the rope too high for their teammates then the center of gravity and effective leverage will be lost for the whole team. Keep the rope as low as possible and your legs and torso near maximum extension at all times. crouching and leaning over your knees weakens your ability to maintain balance.
These methods are actually proper training of heavy line handling for deck crews in the US Navy. It's part of their job to know the best way to leverage a line and coordinate that effort.
Good luck to you! Sounds like fun!!