You can make a lighter non compliant PFD which you fill with other inflatable items, eg Platypus bottles (I carry a 1 and 2 litre bottle, pillows (I carry the Exped Ultralight), wine bladders (who doesn’t have a few of them lying around?) and etc.
Here is the link to Mountain Laurel Designs ‘Thing’ or ‘Mopacka’: https://web.archive.org/web/20100403230340/http://www.mountainlaureldesigns.com/shop/product_info.php?products_id=141 which weighed 4 oz (114 grams) not including its flotation ie the Platypus bottles or inflatable pillows (eg Exped’s Ultralight pillow: http://www.theultralighthiker.com/exped-ultralight-pillow/) but you carry them anyway!
Some folk have made their own. See these two discussions (I have ‘borrowed’ their photos for reference purposes – I hope they don’t mind. Thanks guys): http://packrafting.org/forums/viewtopic.php?t=880 Wine bladder PFD: http://bushwalk.com/forum/viewtopic.php?f=37&t=23122
MLD ‘Thing’
MLD ‘Thing’
DIY ‘Thing’
DIY ‘Thing’
DIY ‘Thing’
DIY ‘Thing’
NB: There is a Facebook Packrafting group: https://www.facebook.com/groups/156445288089260/ as well as (at least) an Ameican Packrafting Association (http://www.packraft.org/American_Packrafting_Association/Home.html) for folks who like to join things. Myself, I am like Groucho Marx: ‘I wouldn’t join anything which would have me as a member’!
See Also:
http://www.theultralighthiker.com/gippsland-pack-rafting-routes/
http://www.theultralighthiker.com/more-about-diy-pfds/
http://www.theultralighthiker.com/ultralight-pack-rafting-life-vest/
http://www.theultralighthiker.com/dusky-track-canoeing-the-seaforth/
http://www.theultralighthiker.com/tanjil-river-canoe-trip/
http://www.theultralighthiker.com/canoeing-gippslands-rivers/
http://www.theultralighthiker.com/canoeing/
http://www.theultralighthiker.com/canoeing-the-thomson-river-gippsland-victoria/
http://www.theultralighthiker.com/videos/thomson-river-canoe-trip/
http://www.theultralighthiker.com/tanjil-river-canoe-trip/
http://www.theultralighthiker.com/tanjil-river-canoeing-update/
http://www.theultralighthiker.com/canoe-clearing/
http://www.theultralighthiker.com/canoeing-the-macalister/
http://www.theultralighthiker.com/tin-canoes/
http://www.theultralighthiker.com/canoeing-the-macalister-river/
http://www.theultralighthiker.com/canoeing-the-macalister-2/
http://www.theultralighthiker.com/canoeing-the-thompson-river/
http://www.theultralighthiker.com/hornet-lite-pack-raft/
http://www.theultralighthiker.com/klymit-packraft/
http://www.theultralighthiker.com/home-made-pack-raft/
http://www.theultralighthiker.com/faux-packraft-vs-alpacka-raft/
http://www.theultralighthiker.com/pack-raft-saves-the-day/
http://www.theultralighthiker.com/pack-rafts/
http://www.theultralighthiker.com/packraft-video/
http://www.theultralighthiker.com/a-gorilla-in-the-bush/