Man, those are some lame "extreme mods".
My "realistic" extreme mod would a forced induction BBC and an adjustible suspension. Complete with a custom wire tuck. Not sure about which body style truck I would go with, though.
My true extreme mod would be a custom built frame with a fully modular suspension. Wanna drive a custom lowered truck through the summer and something with ground clearance and a transfer case in the winter? Wanna run through the mud bogs on the weekend but can't fit in the parking garage at work when you're sitting on 44's? Swap out whatever suspension pieces needed in a couple of hours with just a few major bolts to undo.
The scary thing is, I half think this could be done with a two post lift and a tubular frame design.