First what kind of vehicle do you have?
I looked at rear cargo carriers a couple years ago and decided NOT to go that way. If you strapped it down on its side (laying on a pallet) to the cargo carrier you referenced, it might be okay, but I just wouldn't feel safe with my expensive MAK back there!
I think a trailer (especially a covered one) is your best option if you don't have a pickup truck. I have seen Dave's trailer in person a few times, and it is nice!
If you do have a pickup, then here's how we transport our MAK a few times each year to events and such:
I have a pallet to which we've glued some closed cell foam strips to act as cushioning. I empty the pellets, take the grates, drip pan, heat diffuser, etc. out of the MAK, wrap a strap around the body and lid to keep it closed, then with a helper (usually my son) we lay the MAK down on the pallet, lift it onto the back of my pickup, slide it forward and secure it with a strap if needed.
The other parts get stacked into a clean garbage bag for transporting (which works well after the event since the grates & drip pan are usually a bit greasy).
Best of all it's low-to-no cost and keeps the MAK grill safe!