One word of caution for those who would like to do this...The Crosman 2260 air tube has recently been changed by Crosman.The new tubes are marked: "2260MB". These ARE NOT THE same as the old 2260 tubes. They are 0.049 wall and machine very differently than the old "2260" tubes (0.065 wall). The 2260MB tubes also have a hard step at the front threaded end that will make it very difficult to get it to seal with a Discovery fill adapter. The 2260 tubes are chamfered for a smooth squeeze on the adapter o-rings.I have hydro'd a couple of the newer 2260MB tubes, and they failed at ~4100-4600 psi. In each case, the fill adapter blew out the front.I have assembled about 50 PCP pistols and carbines over the course of 5-6 years, using the 2260 tubes and no failures reported. I wouldn't use a 2260MB tube except for a Co2 cartridge gun.
You are right, cold weather here is detrimental to CO2 use 4-5 months out of the year. By using one of the Bulk fill options available, like this from Bakers...I have a 48ci Paintball tank I fill with 3000psi of air. It has a regulator set to 850-900 psi, (similar to CO2 pressure).I tether that to my CO2 guns that are set-up for bulk fill and I can shoot year around. For those guns, I also have a standard bulk fill set-up with a 20 oz CO2 tank so I can "bulk it up" and shoot "un-tethered" if I want to get away from the bench when it's warm out.