Bwahahaha! Oh, this had me giggling and grinning. What an inspired crossover, and a very, very clever way to incorporate your prompts. Harry and Severus map very well onto James West and Artemis Gordon, and the Wizarding tech works as an excellent stand-in for the Wild West tech from the series.
Also? I'm in awe of all the details. I loved way too many things to mention, and I'm sure I missed many more. But I'm particularly fond of Harry's union suit and butt flap (with built-in Snitches!), Bella's Mordmordre compact, Voldemort in a cowboy hat... and OMG, the last panel. Snape's skinny, endearingly bony legs and grey nightshirt are &hearts, and Harry's wand holster and little Snitch spurs... amazing!