One way around that would be a quick-change battery module so that they don't have to be recharged in situ.
For our 172 project, we discussed this in great detail. There are three practical options for battery location in a 172, and by extension, probably an Islander too: In the wing fuel tank area - great location for best utilization of space, but also the very most difficult place to rapidly swap out batteries. In the cabin, easier to access, and perhaps swap, though handling a many hundred pound load will require a forklift, which will invariably end up accidentally damaging the airframe at some point. This location will use up valuable cabin volume at the C of G, and could be a hazard to occupants. And, my idea was a removable belly pack. Again, it must be at the C of G, and would require a very robust latching mechanism, so lots of airframe mods to carry those loads. The aircraft also has to have adequate ground clearance. But, like changing weapons, it could be done quickly, with the lease risk of airframe damage. All of these were considered major operational obstacles.