They make an insulated version of the Purist now. In fact, it looks like that is the only WB Specialized currently has in stock!
https://www.specialized.com/us/en/shop/equipment/gear/bottles--hydration/c/bottleshydration
Try starting with them completely frozen…or maybe 3/4 of the bottle frozen and then top off with just a little bit of water before you ride. I have done 3+ hour rides in FL during Spring Break in 80*+ weather and still had cool liquids by the end. I found the Podium Chill bottles to be far superior to the Polar bottles.