Having very nearly made this mistake today, how crazy would it be to build a couple of public median turn arounds between Exits 10 and 41 on I90? (Old exits 2 & 3, Lee and Westfield.) Given that Blandford recently voted against a local exit, this 30 mile gap is likely to remain, and is ... Not ideal.
Perhaps something like a very deep U, allowing for ample acceleration and deceleration space? Obviously there are extant emergency vehicle only turn arounds, but they're not configured for safety. I suspect they do provide a good sense of where a public one could be built though. While left side exits aren't ideal either, it does avoid any local impact and minimizes costs with zero bridges. They could be unidirectional too; one for West to East reversals near Westfield and the inverse near Lee.