Skateboard Drivers, Help me "spec" out Flatbed tractor

I am currently a company flatbed driver. New to the game, but learning fast. Know enough to know that, for me, "skateboards" are where I wanna be! In my not too distant future is a plan to O/O. First, probably leased on to the company where I am at and, then, to maybe move to a Mercer or Landstar type of situation with load boards and percentage pay.

I do not want to do a lease purchase. Have good credit and have money set aside. Do not want to buy a brand new truck, but neither do I want to buy one that is too old. Nothing older than 2008..maybe 2007.

You experienced drivers, tell me what you would like/need to see in a flatbed tractor,please. No plans to run oversize or heavy stuff, just standard loads on a 48' flatbed or step-deck trailer.

A tall sleeper in an aero style truck. (i.e. T660/2000/700, 760/780, Cascadia, ProStar, 587/386 etc.) Something common. To be sure, it is strictly a business decision.

Which engine(s) model, HP, so forth and why? 10 speed, 13 speed or what? Wheelbase length and why? With a longer wheelbase, is the sleeper an issue to still have enough overhang on the front for rebar, etc? What would you come up with and why? If you have thoughts about comfort things that are general to OTR, fine, by all means include them, too.

Is running stack(s) off the side pretty much mandatory or can you get away with the stack(s) behind the sleeper? Most of our company trucks (in our flatbed division) have side stacks, but they are not so long of wheelbase, either.

So, drivers, in a few sentences, tell me what you'd suggest for a 48-state OTR Flatbed tractor. Thanks!