I agree with Anne!
We have petrol mowers that we lend out to association members (in non-Covid times, obviously), but we are not insured for the use by others of more risky powered tools such as strimmers.
As for the original question, I would first ask whether there is really a need for such an amount of area to be grassed? We have rules about % that must be under cultivated.
I had grass paths that eventually I covered with weed suppressant fabric, as it was mainly couch grass that kept growing into the beds themselves. I found that my strimmer didn't do the job by about mid-summer, but battery technology has come on in leaps and bounds since then.