I team drove for several months in a straight truck, 22ft box.
We had our bikes with us for about 3 or 4 months. How we did it:
We modified hooks made for mounting bikes in a ceiling joist, or hanging on a wall. The rubber coated 3 inchers that have screw ends on them, like 1.00 at any hardware store. We cut the point off and drilled a hole through them for a cotter pin. We drilled holes in the rail at the top of the box along the sides at the top.
We only had 1 load that actually required us to move them, in which case it was easy, unstrap from wall, take down, and laid them on top of the freight.
Using the cotter pins made it so we could turn the hooks out of the way, or just remove them.
We did however spend more than most on good bikes with the right features. Quick disconnect wheels was a must, in case we needed to remove them to fit in a side box, which they would easily if needed. Our goal was not to have to spend time assembling them and disassembling them when we wanted to use them.
We did a lot of riding on our off time, we had rear racks, with trunks (cloth, water resistant), front bags, and some bungees. Easily hauled 12 packs of pop, new shoes, water for our ride, whatever we wanted within reason.
I plan to put bikes back in the truck this summer for my wife and I. It is great exercise, and just fun for a way to be mobile. not to mention relatively inexpensive.
Don't forget head and tail lights, Even during the day, the strobe feature is a life saver.
~Bill