Not to put you off, but if your credit is so borderline is the expense of a 5er really where you want to be? The voodoo that's in credit scoring won't actually tick up your number all that much from a loan payoff compared to those things that push it down... In other words, there's no direct proportion of change.
Another real expense with the 5er is a competent tow vehicle, and many think because they see half-ton towable 5ers that's really the case. Generally, it's not. It's for those unusual half-tons with high payloads. Even many commonly configured three-quarter-tons aren't enough truck.
As for a hybrid, you will always do better selling privately. Top dollar absolutely requires a used unit in excellent condition as the wholesale market is flooded with used hybrids after the usual Fall through Winter show purchases.