My solution has been to go with a hard tonneau cover and some simple organization items, and it has worked very well for my purposes.
Here is a picture of my setup:
Items I use are a cargo bar across the middle and an organizer that straps nicely to it and stays in place. The bed liner helps keep things from sliding around. This solution gives a decent amount of room both towards both the front and rear. The very back makes for quick access for things like luggage or golf clubs. The front I use for less used things, like camping chairs and some blankets or towels. The middle organizer is compartmentalized and works well for everything else.
What's your specific need for the cross bar? I have hard tonneau, and use a cargo bar, such as this: https://www.amazon.com/gp/product/B004JL0QZA/
I wouldn't use it for real heavy duty stuff, but if you have something lighter to moderate use, it works very well.
I use 2 of these. Not exactly these but a cheaper version
https://www.amazon.com/dp/B004JL0QZA/ref=cm_sw_r_cp_apa_i_ccD1Cb7VV5E8X
The full-bed nets kind of suck if you dont have a full load of crap in there. They're great at keeping stuff in place when its already packed, but for a few items it doesnt help too much. I've found a cargo bar to be more useful, and you can get bag/net accessories for them too.
If you have bed rails, I'd look for something that mounts off them instead. Or put D-rings behind all the rail bolts for more bungee hooks.
> My big question right now is antenna mounting. Even if I wasn't driving an aluminum truck, I wouldn't want a mag-mount scratching my roof to shit. I also would prefer not to drill a hole in my roof. What are my options for mounting? What's going to get me the best performance? Without the roof as a ground plane, am I totally handicapping my antenna?
Can you get coax from the cab to the bed somehow? You could put something like this ratchetting tension bar in the bed, then an NMO mirror mount and a Comet SBB-5NMO
I own that specific tension bar, the outer sleeve does rotate freely so you will have to take that into account somehow.