If you're going with some cheapo muffs, you just have to kludge up something that will stick out further than the levers.
If you pay extra to go with someone who makes them for motorcycles like Hippo Hands, they should be able to give you an easy and reliable solution...
'06 F650GS Dakar
"I never saw no miracle of science That didn't go from a blessing to a curse
I never saw no military solution That didn't always end up as something worse"