I also wear a 16. I am currently using a waterproof leather hunting style boot from Cabela's. I am going on my 3rd season with them and have no complaints. They may not have the full support of the sled/snowboard boots, but given my options, I can't complain. I have put Spenco inserts in the bottom to give arch support and lace them up good. Feet stay dry and warm. Given the quality and the price, I'll likely go back for a second pair when I need to replace them. I had tried on some size 15 boots (HMK possibly), and they were incredibly narrow so there was no way I was getting my foot crammed in there.
I would stay away from Sorel's. I have a pair of those and can't recommend them to be a good riding boot.
Good luck.
