i have this same problem so i shower after 9AM when most folks have left already, but i'm lucky to get to be able to do that cause of my work schedule being in a different time zone from where i live. i also get hot water late at night when not too many folks are awake.

i don't know of any way to make the water hot all the time short of redoing the plumbing and installing your own water heater though :[

maybe someone who knows more about plumbing will have better ideas