Private WiFi network between OSX and Android
Other than your self-found answer, my suggestion would have been to get an Airport Express base station and take it with you all the time.  All it is requiring is an extra power outlet.

Any other router would possibly do as well, but the Airport Express is fairly small and fits into almost every pocket.

Since you frequently do presentations and it can be used at home or elsewhere as well, the price tag would not be too bad either.