And hey couple comments on the above comments as long as I'm here: the 30/60 towers are about 1" lower than the 45° towers, and each have about 3/4" of up and down travel to them. The 30/60 towers will only work if you don't have a factory rack, but the 45° towers would allow you to mount something above the factory rack. We originally made the 30/60's to get a wider stance, so our same racks that fit the 80's and 100's could also fit the 60/62 series, but then later realized they could also be used on 80's for a lower profile rack.
The upside of the 30/60's on the 80 is you get more clearance for garages, a little less drag, etc. The downside is it can be a pain to put your arm under there if you have to reach all the way to the middle for a u-bold for a box or something. You can usually get past this by mounting the inside mounts first with the box or tent towards the outside, then sliding whatever it is over. there are 80's running 4" Slee lifts and 315's, running 30/60 towers and Expo racks (basket upwards) and driving inside standard 7' garages. it's tight, and every garage, and every ride height is different, but it's definitely possible.
Also to comment on the "stuff sliding off" thought, you strap it down, same as you would if you had a basket. We'll lob camping chairs, sleeping bags, and a 10x10 awning up there, then use one of those spider web bungee things secured to the perimeter. For heavier or larger items we use ratchet straps. Even when I had a big basket rack I'd never just throw something up there without also using some straps, so I've found it's actually no different without walls. Just makes it easier for loading, unloading, and RTT's.
