I have two sets of components up front, and two mids in the rear wall, (and I'm in a regular cab pickup). I think it's more of asking yourself the differences between the two.
Do you have a large vehicle, where there IS a rear stage?
Do you have people in the back that you want to hear the music as well as they would if they were in the front.
Are you an uber driver?
I always look at it as, I would rather have a front fill though, no matter the music. It's not like surround sound. It's not like watching tv where the image is the main sensory input, and the audio is secondary. Then surround sound is there to help you feel immersed into the what the idea that the show is trying to sell you on.
In your vehicle, you are the focal point, and your stage is set around you, and trying to focus on you. Your drivers seat is not going to change, (but maybe you want everyone else to hear it is well as you can, which isn't perfectly possible, but could be close enough if loud enough).
Call me selfish, but I play MY music, in MY truck, for ME.
I can barely notice the rears, but I can notice them.