my husband made a very simple wooden structure for the bed of our pickup truck. It's a piece of plywood with bike mounting gizmos on it.
S you can just clip the bikes in (take front wheels off) and stand 3 bikes up in a row inthere (4? can't remember) he's a complete bone head when it comes to
building stuff and mechanics, so if he can do it, anyone can.

having said that; we get better gas mileage with our buick regal so we usually don't use the truck anymore, we have racks on the top of our car. It's pretty yucky if it rains though.
and when it's just me, i put my bike inside my honda civic, there's not much
room for it to slide around in there