Kimmyt.. I ride regularly with a friend who has a very small compact frame... she actually got a seat bag that is triangular and fits between the top tube and the downtube... in that triangle it makes... then she got one of the bottle holders that holds 2 bottles off the rear of the saddle... so when she rides she has 3 bottles with her. (Hey PurePink! Where are you? Respond to this and tell her what brand you use...)
It gets hot here too, and I really suffer with it... I've lived here for years and no amount of getting used to it has helped me... on the really hot days I do freeze at least 1/2 my bottle (lay in freezer on it's side and then top with ice water when you're ready to go) and I drink a MINIMUM of 1 bottle per hour on ANY ride... that is what works for me... I use Cytomax as well which helps... the electrolytes really help replace the salt I loose from sweating so bad when it's 100 degrees out...
and lastly, I just ride easier when it's that hot out. I don't go as fast or as hard... and I choose routes that aren't as intensive... I still ride, but I KNOW the heat is tough for me, so I just take it easier... I also try to ride really early or really late in the day... never midday...
I have also been known to douse myself with a water bottle if I find a spot where I can refill with cold water... and sometimes that means BUYING water at the 7-11...
oh... there is nothing so great as a waterbottle overhead on a hot day!
There is a fine line between "hobby" and "mental illness".