Thanks for the pointers, guys.
I ended up going with Bagmaster's AR-15 Pro Shooter's bag from Brownells (100-000-926):
[url]http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=17334[/url]
and Creedmoor Sports' roll-up shooting mat:
[url]http://www.creedmoorsports.com/N040a.htm[/url]
Both are a little pricey, but both are very good quality.