Well, I haven't updated this in a while as the Ranger has been out of commission due to a blown brake line and me having no time to fix it. While it's been sitting, I picked up a set of new wheels/tires for only $150 (and some pizza pans) and found a matching LEER cap online for only $100. I haven't run an entire tank through it yet, but the weight of the cap may hurt more than the aerodynamics help, we'll see. I just mounted up the wheels/tires last night. The contact patch is about 1cm wider than my previous tires, but they're a harder compound than those winter tires were. I'm running them at 42psi.
I have put in a few pieces of ABS sheeting to try and seal up the underbelly as well. I'll try and get some pics of that sometime within the next week or so.
This week, I am going to make some sort of quick-disconnect for the cross-bars on the Cap. I don't need them every day, but it'd be nice to be able to put them on fairly quickly when I want them. I'll also be finding a way to mount the pizza pans so that they don't rotate while mounted.
Unfortunately, I have realized that I have a small gas leak from where the filler hose meets the gas tank as well as some rust issues in the rear of the truck. I will be tearing in to it again within the next month or so.
Here's where it sits now: