We’re back out on a limb here, but why not install a Mazda rotary in a lightweight sand or mud 4x4? The ’78-’85 12A and the ’86-’96 13B engines can handle heavy turbocharging, they wind to the moon, and they’ve got very few moving parts to fail out in the field. In 1987 the 13B got a turbo for 185hp, which ultimately grew to 200hp by 1989, 255 by 1992, 265 by 1996, and 280 by 1999. Not bad for an engine that weighs less than 275 pounds. And you can adapt them to a Ford T-5!