I think it's totally do-able. With any bike, even a road bike with drop bars, a headwind sucks. You can always try to tuck down on the beach cruiser, but end of day you just have to tough it out.

One thing you may want to consider is changing the gearing. Many stock singlespeed beach cruisers spin out at about 10mph, going to a bigger chainring or smaller rear freewheel can really help the top speed.

I ride a fixed Surly Cross Check now, but have used a beach cruiser for many years as my "do anything" bike. They are awesome, and the ease of use and maintenance inherent to a coaster brake is not to be dismissed lightly IMHO.

Steve