Wow 4E width, no wonder you are having problems. There has got to be some company that makes custom cycling shoes. Even Sidi mega are only designed for like E or 2E width I believe.
You might try building you own shoes out of some football cleats since they would be available in wide widths for big guys and use some carbon fiber and epoxy to make a cleat mounting surface and stiffen the sole.
Here is a link to some 4E wide football cleats. I think you could modify something like this at a reasonable price compared to getting custom shoes.
http://www.newbalancetampa.com/shop/...model=MF1200MK
Of course these Rocket7 shoes would be the best but pricy.
http://www.rocket7.com/