I don't mean this in any kind of negative way (infact quite the opposite) but your wife does not sound like the "average woman". I know that my girlfriend would not want to have sex with, or honestly get anywhere near something that was 10" by 8"!
I'm not saying that every woman just really wants an average size penis, but I am saying that a fair amount of women don't want a huge one and are fine and dandy with an average guy. Some of these women might be embarassed to buy a big one but it also appears that average size dildo's are still the most popularly ordered online, which would cut out the embarassment factor. That's pretty awesome though that your wife can take that big and is open to different sexual fantasies and things. Sometimes I wish my girlfriend was a bit more experimental but it's all good, maybe in time...