Guadelupes in May/June? Are you talking about trying to stay out for 5-7 days, with a dog? Better get a Gregory Palisades, or Osprey Argon, or something that carries a ton, because at a gallon of water per day, plus whatever you carry for a dog, you'll be loaded. So where in NM are you talking about?
Pad - I'd look at an inflatable, like the POE Ether Thermo.
Sleeping bag - barring the odd cold front, for Texas I'd plan on 50-60s at night. Don't know where you're going in NM, so I can't say.
Boots - bag the boots. I use GoLite trail runners in the Guadelupe/Davis/Sangre de Cristo mountains all the time.
A little hot? I'd plan on a minimum of the upper 80s during May. Maybe worse. And unless something changes, winds in the 30s, and higher. You might get lucky and catch a few calm days, but that has been the exception lately.