One thing you don't address is the purpose/intent of your truck. It's hard to recommend a solution if we don't fully understand the problem. Do you want an as designed/intended/capable truck or do you want a cruiser? That will help shape your solution. If you want a fully functional truck that will routinely do work and occasionally cruise for longer distances, that leads you down a certain path. If you want a cruiser that may occasionally do some real work, that leads you down a different path. It all comes down to where you are willing to accept "risk." I don't mean risk from a safety standpoint; more of a capabilities standpoint.
I will make the stereotyped conclusion that as a 15 year old you probably want cool vehicle to drive to high school and have a really cool vehicle to cruise in on your soon to be numerous dates (because you drive a really cool truck). :-) If that is your intent, then you should be willing to accept risk in the workhorse nature of your truck. With an overdrive transmission/rear end gear swap/taller tires you can get comfortable cruising without having to wind up the motor. You will probably sacrifice hauling and towing capacity or at least make it more difficult. If on the other hand your intent is to routinely use your truck to do real work hauling/towing and occasionally go for a cruise that may lead to the higher revving engine. You get to keep all the functionality of your truck while accepting risk in the quite/comfortable cruising area.
Bottom line is you need to clearly define the problem. I believe it was Einstein that said "if I had one hour to solve a problem that my life depended on, I would spend 55 minutes studying the problem and 5 minutes solving it."
