By Paolo Sandoval Hard as it may be to believe, summer’s days are numbered, and there’s zero denying that cooling temps and transitioning foliage make for the best to enjoy all that nature has to offer, from a half-hour hike to a two-week camping stint in the backcountry. Speaking of Backcountry, the Salt Lake City-based outdoors retailer is throwing their Summer Send-Off Sale, a massive event chock full of thousands of outdoor staples — hiking boots, necessary gear and the like — from top brands like Merrell, The North Face, RUMPL and more, marked down by up to 60%. It’s the perfect time to r…