In my region, a medical evacuation by air ambulance is referred to as a "medevac" (also spelled medivac). Although this is a noun, in my observation it is more frequently used as a verb ("I'm going to have to medevac you," the doctor said.). I want to spell the past participle "medevaced" but this reads -- to me -- as though it should be pronounced medevassed (rhyming with 'vast') or even medevayssed (rhyming with 'waste') because there's an E after the C, making it soft.
With "old words" like the verb "to arc," there appears to be a solution. I have seen the past participle of "arc" spelled "arcked" (and the gerund "arcking") though both more commonly I have seen spelled without the K. Although this drives me crazy because "arced" looks like it should sound like "arssed," at least there is an established alternative, the addition of the K. But because "medevac" is a new word (according to Merriam-Webster the noun entered the language in 1966, and there still appears no agreement on how to spell it), and because "evacuation" does not have a K, I am reluctant to add the K that "arc" enjoys.
Is there a way around this problem?