Try getting a good look at the Baja Outback Legacy, think about moving the back cap forward, losing the rear doors, as much as can allowing for front seat travel and tilt. See if replacement sheet metal is available to assemble the hardest parts of it. Then fill the gaps. Find an H6 wagon, maybe upgrade to 5x114 hubs if able to for bigger bearings, H6 brakes are the largest rears that will fit 16", maybe 15" for LT tires for added weight carrying... but 5,000 lbs is a Big ask. Try a Tribeca? Or lighten the load.
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