If you sell it, you don't have to change it back. Just include the parts so the buyer, if they so choose, can change it if they want. Maybe the next owner will only be 5'6" and want it exactly the height you have it.
If you want to make aero mods, the general consensus on these pages is that a front air dam, though it increases your frontal area, radically decreases how much drag the very, very bad underside of a truck contributes. You get like 75% of the results of a full belly pan for 25% of the work and expense. Side skirts and tire spats can help too, but the air dam will be your biggest bang for the buck.
For example, look at ecomodder Big Dave who in 2008 modded his F350 to very un-F350 economy:
https://ecomodder.com/forum/showthre...ckup-3171.html
Notice he lowered his truck too. He also had a whaleback cap on his bed so you can't attribute all of that result to an air dam.
In the time I've been recording its results here on EM, my truck has saved over $1100 vs. the EPA sticker. That pays for some mods. If it takes time, it takes time. Wait it out.