In WI you can't find anything but 10% ethanol mix. It's all they sell.
I have been safely running 87 octane regular gas with 10% ethanol for over a year in these trucks and have had ZERO issues.
BTW the higher octane does nothing for these low compression two strokes. Lower octane burns slower, so a lot of heat is pushed out the exhaust in these engines, thus over heating the exhaust ports.
There is zero reason to use anything but 87 octane regular.