That was me a couple of years ago, then I saw the light. Now the truck gets less than 1000 miles per year, only used when I need to haul.
I spent lots of time and money trying to get better mpg with the truck, in the end going from 12 to 14 mpg wasn't enough for me.

Ditto that.

We just sold our truck today. My parents have a truck we can borrow when we truly need one, so now in addition to our $200 lower payment, hopefully our fuel cost will be cut in half as well.

I check my mileage at every fill up. This site posts gaslogs? Where?

Ya know, a truck is nice to have, being able to average ~30mpg and all. If I got it up to ~50mpg (unloaded ~50mph cruise) I'd be happy.
On the tabs right under the logo at the top of the page, click on garage. From there, click on 'add gaslog entry' to the far right of your truck. Fill out the form and click on the 'add gaslog entry' at the bottom of the page.

Enter your vehicle in the garage....

You won't lose functionality. My air dam in the front was way low last summer and I didn't have any problems even when going to the cabin and running across the yard.

My aero mods.

I didn't read every post here, but wanted to add that you can get free coroplast signs at your local recycling center( Or at least I can at mine ) with which to make a smooth underbelly.

Just use some short self tapping screws and drill right into the frame. ( You only need a few so don't go wild, as this may weaken the rigidity of the frame.)
I try to think ahead to which parts of the chassis flex up and down or need to turn before covering them up .
I also think about areas that would allow water to enter between the chassis and the coroplast, since you don't want the stuff to rip off when you go through heavy rain.
To cover my gas tank, I used the tank's straps to hold the coroplast in place. ( The last thing you want to do is drill into the tank !!! )

Keep at least a couple of inches clearance from the exaust and other hot areas as well. If your truck has a drive shaft, I would keep some clearance there too ( friction would create a fire )

I just did a half arsed job of drilling some coroplast to my car, and have to say it has been a resounding sucess !
I have not had any problems, despite driving through loads of rain and hundreds of miles.
Since the stuff comes white and looks stupid hanging off of your car, I used black tempera paint to paint it ... just to see what it would look like ...and despite tempera paint being waterbased, it still has not come off yet.
( And I didn't have to pollute the air with enamel paint fumes either ;-D )

im guessing you dont get much snow or salt do you in texas...

if i were to do that up here i would trap so much saltwater it would rust out every little bit more than it already is...but i can see how it might be plausible if you can get the stuff for free. so props to you for doing all this for prolly under $10 (paint and screws).

but i hate to tell ya, i did your paint fumes damage for you...7 spray cans of flatblack to paint by truck bed...cost a whole whopping $7 too :D amazingly hasnt flaked off or scratched off dispite all the crap ive thrown back there. but if it does then ill spray some more paint over the scratch..

How about a cover like this? Has anybody used one and noticed a difference?
https://www.central4wd.com/_files/_im...176.4panel.jpg

Actually, I just found something in another thread:
https://www.autobloggreen.com/2006/08...tonneau-cover/

From what I have read, a simple tonneau cover is probably the most effective and easiest fuel economy mod for pickups, providing around 10% improvement. I forget where I read that though, and it might have been at a website trying to sell tonneau covers FWIW.