There are plenty of shorter wrenches out there that would easily suffice. I carry the Craftsman 15mm stubby.
http://www.sears.com/shc/s/p_10153_1...u=00944117000P
Tons of "designer" wrenches have been created in the last few years for the fixed gear crowed since most those wheelsets use 15mm bolts to attach the wheelset to the frame. Search the forums, specifically the FGSS sub forum for many more options.