If you are comfortable in an 8.5D Indy, then 8.5E Barrie is going to be substantially wider and offer more volume overall. Of course, they are boots so you will be able to lace them up to get a better fit and you can always wear heavier socks to fill them out.
Standard caveat is that these are $700+, so perhaps you want to wait to get a size you know is right for you.
Bottom line, my opinion is that 8.5E could work for you. It all depends on how committed you are to making it work.
Thanks so much for the advice guys! I think I'll hold off. The 8.5D was available two nights ago, but was sold out by the time I was ready to pull the trigger. I've wanted the Color 8 Chukkas for awhile, so I think I'll try an 8.5D and see how it goes before being tempted by another pre-order. :)