Has anybody used one of these? I'd have to check it out, but looks like we could just pack all clothes/sheets/foldable items into normal storage containers and strap them down.
What are the negatives to this option?
That's what I do when we're doing longer distance work with our Volt. People and a few things inside, cargo rack on the outside with the light, fluffy stuff (sleeping bags, pillows, coats, sweatshirts, etc). I literally can't see it from inside the car, and not having the back piled up improves visibility.
The downside is just that you need a receiver, and, IMO, the 1.25" stuff doesn't have the torsional rigidity I'd prefer for this sort of thing (IMO, there's no reason to get a 1.25" receiver). That's one of the main reasons I put a 2" receiver on the Volt (same size receiver as a typical truck receiver, and, yes, I can swap stingers between vehicles if I need).
The Harbor Freight one is probably fine. Mine's custom built for the car, because it needs a bit of a weird drop. My hitch is up behind the license plate, so it's actually higher than my truck hitch. It's also powder coated to match the car. Because if you're going to go custom,
go full custom.
As far as I can tell, there's no impact to fuel burn with it back there. The Volt's highway MPG is nothing to write home about, about 35-38mpg loaded doing 75mph (interstate speeds out here are quite ludicrous, though fuel burn isn't
that much worse at 85mph), with or without the rack back there. I'm certain a roofrack would impact fuel burn noticeably.