Hi monahanajj and welcome to MySwag,
Fantastic place Moreton Island, you will have a great time.
Track conditions over there vary between easy and moderate, your 80 will do it easy, just remember to lower tyre pressures. Start with 22psi in rear and 20psi in the front, if you still find it's a bit of a battle, drop down to 18psi and further if the need arises...don't forget to do the same with the trailer.
If possible, pack the trailer with heaviest items over the axle and distribute the lighter stuff evenly across the rest of the trailer to keep it well balanced.
And above all have a great time and hope you catch some fish.