I think the closest you can come without compromising *all* ankle support and shin protection would be the Sidi Discoveries/Aerostich CBTs. For obvious reasons, Trials boots are very flexible at the ankle.
Personally, I've made the switch to wearing MX boots all of the time. I wear Sidi Flex Force and Sidi Crossfiles, which both have a hinge at the ankle (easier shifting/braking) but offer excellent armored support and are quite comfortable (albeit heavy) while walking around. I had a backwards slide-get-off in June that twisted and sandwiched my lower leg between a rock wall and the bike, but instead of a break I only suffered a mild sprain. I'll happily trade a little awkwardness for good protection.