The best bags in my opinion are the Western Mountaineering range. They do a wide shoulder girth at 64" for some models. The Alpinlite would easily keep you toasty at 30 degrees.
Cheap they are not, but if you want something you will love owning, you have to pay.
If you sleep warm, you may get away with a Megalite at 30*:
Otherwise, Marmot do an 8" extender to widen their bags I think. Your other option is to switch to a quilt and get it custom built by one of the MYOG experts here. I had a light quilt made by Tim Marshall which is superb, and was very fairly priced.