Glad you've started asking questions, It took me a while to start, but it's been brilliant.
I had a week around Pelion last winter, via Maggs Spur - lovely route, and much gentler climb, but i agree it was a bit of a nuisance having a big pack. It's an extra handy track if climbing Pillinger on the way in or out (which i
highly recommend - amphitheatre view of the Overland Track, Ducane Range etc, not sure why i hear so little about it)
You can certainly do Pillinger from the ART - just a bit scrubby in places.
Went in by Arm River Track for a week this year - the track's reputation had put me off, but even for tortoises (take an average walking time and maybe double it), it really wasn't a big deal.
If it's any consolation, I finally got to climb Ossa this year, after 6 times at Pelion Gap in sleet/snow/blizzard/invisible mountain conditions.

Still have to go back for the view south. Well worth the effort, though.
Our winter attempt was thwarted by ice - no hand/footholds on a bit of a rock scramble, just slick ice about 3 cms thick, that wasn't going to work. But we did get
awesome views from near the top of Pelion East - magic stuff.
Not sure if you're planning on Oakleigh, but i suggest you go for it if you have time. it seems to be clear more often than Ossa, and being a shorter walk, you can start later if the weather improves. I did wonder why people bothered with the mud - until i went myself. It's watery mud (at least where i went in up to my waist...) rather than boot-sucking mud, and it's one of the best views I've seen.
Have fun!!