Hi Biffo, there is a nice pathway from mucross around the shore that ends at caravan park, but dogs are not allowed on to the caravan park, people are though and it does have a reasonable restrauant and bar. This pathway is used for dog walking, also its a quiet road back to kesh (1 mile) and again used for dog walking.
Yes you can take back roads depending on where you are travelling from, the mucross road is a dead end road but you dont have to go through the village to get to it.
The toilet facilities are open to the public, there is a shower block atr the kesh river carpark which I think takes card. Hope that helps regards
Anna