With the type of driving that you have described, your front diff will handle those situations with ease. Just do the upgrades that you have decided on and call it a day. Those Avi's ride to nice, and are to civilized to do an axle swap for those conditions. As a former Avi driver and K5 owner with 38's, bring the Blazer back to life and enjoy that for off-roading. Hell either way you go, both would be great. I have always been a fan of Lock-Right lockers. Had them in both the front and rear of the K5. No problems and I was pushing it with 38.5's on 10 bolts and I did everything in that truck. haha. Just remember if you do decide to go with a lift and tires check the locker manufacture because only a couple warranty the locker above 33 inch tires. Good Luck

Jay