Hi Emma,
Plenty of perspectives.
There's a waterfall near Lake Will to give you a side trip on day 2 to Windemere.
Hey SBS, do you mean Innes Falls? Last time I was there we decided against the scrub bash it now appears to be - but there was a lot of ice, and I wasn't well, so maybe it's fine.
- Emma, I'd highly recommend Mt Oakleigh as your main mountain side trip. Out of 200+ mountains I've been up in Tassie, Oakleigh remains one of my favourites. And at 1286m, it's significantly lower than the other contenders for you. It's gorgeous looking down on the spires, with little rock gardens nestled among them. If you have views, there's a wonderful perspective on the area, with a number of horizontal layers - Pine Forest Moor, Pelion Plains, Forth Valley etc. And all the mountains of course. I haven't made use of the spiffy boardwalk yet, but I suspect it would help you avoid the worst of the mud.
And 1+ for SBS's suggestion of just going up the slopes of Ossa or Pelion East.
- As you are going light weight, I think Windermere is still a good option for Plan A night 1, unless you want a couple of hours to explore the waterfalls at Waterfall Valley. You can test your fitness closer to the time with a loaded pack and the same sort of elevation gain you'll expect on Day 1.
If you don't mind missing the 'official' start of the track, you could save time on day 1 by starting at Dove Lake and going up via the boatshed and 'rough' track to Marions, which has been upgraded. There are steep bits, but it's shorter and there are plenty of great views, and chains to help pull yourself up little bits. Not hard if you pace yourself. Many locals prefer it.
Re the deadline for transport from Lake St Clair: I know I'm biased, recently having a trip turned on its head when our boat booking was cancelled. In summer, there's much less chance of that. But people do get bumped off their bookings occasionally, and if the weather is too wild, the boat would be cancelled. You should be able to check that when you radio in from Narcissus, or have a reasonably up to date forecast from anyone with Telstra who had been up high enough in the couple of days before.
-Tall mountain-leapers can do Windy Ridge to Narcissus in 2 hours, but PWS suggests 3 - 4 for the 9 kms - as I'm sure you'll know. It's not fast over tree roots in the forest, and those without long legs can find it hard to make up time striding out along the boardwalk with a full pack.
- Pine Valley is lovely forest walk, and if it's clear, the views of spectacular mountains from the helipad are great. But personally, if I didn't have time to go up to the Acropolis or the Labyrinth, I'd probably opt for more time on the main track. I find the forest along the lake rather lovely too, especially if you stop in at the little beaches along the way for a view back. If you camp the last night at Echo Point (see rat warnings on another thread), you'd have more control over when you get back to Cynthia Bay. You'd still need to allow heaps of time, as again, it's not fast walking with tree roots etc in places.
Enjoy!!