Here's my .02 on a bike rack - I could not find one I liked that would let me mount the bike in the bed, and did not want to have to remove the front wheel every time to attach using a skewer, so I made my own with a piece of aluminum angle. It attaches to 2 of the tie down holes so nothing on the truck has to be drilled. I took 2 of the DeeZee tiedowns and milled off the loop to make a flat attachment point for the angle, bolted on the angle, and added a couple of pieces of plastic where the tire fits in to give the tire a little more support. The notch in the angle and tie straps keep the rear tire in place.
This is probably the least floppy bike rack I have used (I hate looking in the mirror and seeing the bike wiggling - even though it is going nowhere, I just don't like it).
Easy to make, easy to install, and it does not get in the way if you leave it in the bed all of the time. A 26" or 27.5" bike would probably fit in with the front tire straight, but a 29 will not unless it is really a small frame.
I only carry one bike, but it looks like if you ran the angle all the way across the bed you could carry 3 easily.