What WM bag do you have now?
They make a few wider models in the 15�s like the Alpinlite (64�), Badger (66�) and the ponderosa (67�) which is a semi rectangular bag.
For some reason my WM Antelope fits tighter than it did 20 years ago..........
I've been eyeballing a Ponderosa, my wallet cringes though.......
I picked up a never used Big Agnes Encampment and Big Agnes insulated pad cheap enough I figured I didn't have much to lose. Have only spent 3 nights in it, but so far I like it.
Casey