Alright, got some more info on the AC690. There's an AD on the airplane limiting the airplane to 180kts in turbulence. Apparently a few lost their tail cones in severe turb and crashed. No issues with the CG fully loaded.
The guy I've talked to has never heard of a TPE-331 failure, but has heard of a couple PT-6 failures on the Caravan or King Air. He says the 331 is not for dummies. Really easy to hot start, but the 331 is way more efficient than the PT-6 and the 690 is faster than a King Air, so it's a double win.
Easy to fly, alot like the 500 (I'll vouch for that, like a Cessna 206 with two engines,) will climb on one engine, gear and flaps down.
The spar is an issue. You can get them with the 36-month inspection (a spar cap is installed to prevent corrosion) or have the entire spar replaced (no more inspections ever) but those are really pricey.
He says to expect to pay anywhere from $600k-$850k on a really good machine, one with all the work done, and if you do buy one, always get the pre-buy done at a Aero Commander service center, like Aero Air or Byerly.
As far as your cargo, I'm sure a wheel would fit no problem, its just the door is in the front and it would have to be strapped down in front if you have passengers, but it's really easy to load and shouldn't have a problem since the door is right off the ground.
I'm not sure if unimproved airstrips would be a problem. The main landing gear on the Commanders are virtually indestructible. The nose is a little bit more fragile (we've had a couple snap off when the line tried to tow with the parking brake set.)
If you have anymore questions, I'll be here all day!