I have some Lake CX130 size 45 EE road shoes which were actually wide enough for my wide feet but had more vertical space (volume) than I wanted so I added a shim and now they're perfect. However I, like you, want a shoe that I can walk in a little bit, so I've been shopping for a wide, stiff mtb shoe.

Lake's MX130 is the mountain bike version of the CX130 shoe but, unfortunately, the fit isn't nearly as wide so I'd say it's not the first one you should try.

I tried on one of Shimano's upper end EE-sized mtb shoes but it's toe box tapers too much for my little toe. It seems that all of Shimano's shoes have toe boxes which taper too severely.

I finally tried on some Specialized shoes. Their toe boxes seem to be more square in shape than tapered like the Shimanos. I tried on a 45 Wide and it seems wide enough that I think I could go to a 44.5 Wide. If you're willing to part with around $225, they're the BG PRO CARBON MTB SHOE.

Last, I ordered some Shimano M225's in a wide size, as desribed above. If your forefoot isn't as square as mine, they may fit. PM me if you're interested.