I don't have boards in the bathroom but for the rest of the house where I do have them, I use eucalyptus oil and hot water. It's a disinfectant and smells delish. In toilets etc. I use white king - my one and only 'nasty" cleaner left in the house because I love how it cleans compared to anything else and just can't drop it yet!
Tanstar - what is the ratio of eucalyptus oil to water?