When I was looking at the Grand Marquis GS in 2004 I sat in a Lincoln Navigator and I hated it because I could barely see over the dash and I’m about 5’11" tall. It really felt like I was sitting in a hole trying to look out. I know you wouldn’t get very good gas mileage and don’t know whether an older model would be available or what an older model would cost, but a Lincoln Navigator, Ford Explorer, or Ford Expedition might fit you perfectly.