I havent read about any females using pantyhose to keep things in place, but I think it is going to work.
Ive actually read some accounts (elsewhere) of female subbers wearing thigh-highs and hiding the bottle there - all with successful results.
I know I am going to sweat to death wearing hose in 95 degree weather, and I hope it doesnt affect the temp too much.
Hopefully the clinic that you will be using (and waiting inside) will not have a broken A/C system. Most facilities in hotter areas of the country have their A/C systems jacked up quite high during the summer months.

A tipper in regards to waiting inside the "ice cold A/C" clinic: Avoid cold seats! Cold seats can cause the temp drop at the bottle. Stand up instead (and not in an area where a ceiling A/C duct is directly blowing) and wait for a seat that had just been vacated by a warm body. :thumbsup: