I don't know what kind of Gatoraid bottles you have but the older Adventuror I had fit into a full one just fine. These are the .6L bottles. Any spillage from the full bottle just helps wash the threading clear.
I recently lost mine in a hike up through the Dix Mountains (ADK's) and replaced it with the newer Opti. (A slip tore open my side pouch which I didn't notice for several miles...the next watering hole. I wrap it in my glove liners and lost one of those, too.)
In the three/four years I had it, I had no problems with it, except the first time out. I had tried it at home and left the batteries in (rechargables.) They were flat two days later on the trail. A couple sets of lithium batteries were purchased after that and one was turned over, except in use. The idle current drain was quite high. End of battery usage problems.
Rechargables worked, OK, but were not weight efficient. For quick weekend trips, They are OK, but it is easier to use the lithium, ones. Though, I have heard of a couple people saying they were not the best for it... I picked up 4 sets at Battery Junction along with a recharger. These were the same batteries that came with the Adventurer. The whole kit (Solar charger, batteries and Adventurer) cost about $160 at the time (newly released) soo, $36 is a hell of a good price. The solar charger was worthless (the ADK's never has enough sunlight.) The rechagable batteries last about 50 chargings or about two years, but they decrease in power...from about 30 to 20 in the first 10 chargings, 20 to 10 uses over the next 30 chargings. . .
Getting back to gatoraid bottles, the Opti works as well, fully in, but not falling into the gatoraid bottle. When done treating water (mostly not necessary...but...) replace the top while slowly sgueezing. This will wash the threads off pretty well.