You mention "chain hotel", which sounds promising - because unless it is one of the many small, family-run independent hotels in the countryside, you'll most likely get away with it just like you would in the US. The larger/more international the hotel, the lower the chance they'll pay much attention. Make the booking before the 18th birthday, and you'll even have an excuse story up your sleeve as a bonus

[Don't like "cheating" in general, but do believe the "p.P. tradition" is anachronistc]