Thanks for your reply Ryan. The inline idea was already done back in 2010. It was done by this guy and it worked quite well:
David Hrivnak's 2004 Chevrolet Avalanche
I was able to talk to him about a year ago and he explained a little on how he did it. Pretty straightforward. I still want to do it another way as well.
There are about 3 other ways others have done this. I know this is a hypermiling forum but I can provide links if anyone wants to see them. I just believe they were pretty awesome approaches and I have interest in this as well as what hypermilers do.
As for the diesel, I know that will be too involved for me.
Thanks again