Thanks for the info you posted up about the oil sump setup. Didn't realize it would need to breathe but that makes perfect sense.
Looks like you should be ready to rock when the weather warms up. What is left to do?
PS - you need a Reznor or similar gas heater in your garage. Should be pretty easy to plumb in with your exposed framing. With as much time as you spend out there I figured you'd have something to keep it warm. We just built a new home so I was able to get gas heat, 220 and accommodations for a lift in place up front. I relied on a Kerosene heater in my old garage and it kept it warm but the fumes were too much.