I love my Lomax Stance Cover. In my opinion it's the nicest low profile cover for our trucks. You don't have to drill holes and worry about drain tubes. Anything from Lomax is far superior to Bakflip.
I replaced my Hankooks with falken wildpeak ht02. It's a very nice quiet ride. I didn't want A/T tires. They pick up two many rocks and fling them at your truck. I haven't noticed any drop in MPG's either.
I love the single I have a hard angle to get in my garage so the double door would have made getting into the one bay a nightmare. The doors is 16' wide and 8' tall.
If I could have went bigger I would have. Any bigger and I would have needed engineering of a stormwater management plan. Not worth the trouble for the maximum size of 24x30. I did go with 10' walls and scissor trusses to really open it up with the limited floor space
More then likely you will not find an experienced tech working at Discount tire. All techs need to start somewhere. It's just unfortunate when the start is working on your truck.