With a Dually I assume your looking for a Fifth Wheel? The top of the line Toy Haulers have a top of the line price as well, $70k to 100k...
If I was buying today I would be looking at the Amped 32gs. It's not a Fifth Wheel, I just like the looks and Fifth wheel floor plan in a bumper pull Toy Hauler.
http://www.floydsrvs.com/New-Inventory-2015-EverGreen-Toy-Hauler-Amped-32GS-Norman-Oklahoma-812209You could put the Razor in the garage and the dirt bikes in the back of the truck! The one I looked at was washer and dryer ready as well.... I don't think you would get two dirt bikes and a razor in a 12 foot garage..
OSB is being used in the home buiding industry more than plywood as well. OSB is cheaper but has a stronger shear rating...
2017 Coleman 300tq by Dutchman Toy Hauler. 34.5 feet long and under 10k Gross. 500 watt Solar 2000 watt Inverter, 1999 Ford F250 2WD 7.3 4R100 DP Tuner, S&B Cold Air Intake, Gauges, 6.0 Trans Cooler, Air Bags.