Hope I'm not too late in posting... your Highland Trail plan should be no problem based on what sounds like a pretty decent personal fitness level. It's certainly no more demanding than Centennial Ridges (just longer). Don't miss the Starling Lake Lookout if you're hitting that section of trail - well worth the short detour.
As for gear tips, I highly recommend warm under clothing and a tuque - the nights can feel colder than anticipated. Lots of light weight high calorie foods will be appreciated as it's amazing how much energy is burned, even when resting in cool temps. Having said that, you don't want to burden yourself with too much food - better to be marginally hungry than walk out with 5 extra pounds I say! As I like camp fires (modest ones), I always bring a small folding saw. When foraging for wood, I look for hardwood/maple stands and search for fallen limbs that are off the ground. Birch bark is an awesome fire starter (but not from live trees). I always carry a backup pack of matches and often a small lighter - just in case. I never carry more than 1 litre of water at any given time as there's lots of spots to re-stock - at 2.2 lbs/litre, it's heavy. Finally, hiking poles are another must for me, but that's a personal preference of course.
Hope this helps!
Rich