On the subject of trays, whilst the car dealers will push you towards a "branded" tray, you can have whatever you want. On the farm we always buy bare cab-chassis vehicles and then get custom made trays to suit our requirements. For example, I like trays with tool boxes under both sides and a rolla-drawer in the middle. I also have the headboard made only very slightly taller than the roof (wind resistance and clearance in car parks) but then have an easily removable extension to add height when I want to carry long objects. That extension exactly matches the height of a Thule roof bar on the cab, and I have a removable rear bar to give three points of support for long objects. Because it's a farm vehicle I also have "extra high" extensions that allow me to carry farm gates high enough to get a petrol driven compressor (for post driving) on the tray beneath them. The tray also has attachment points for a stock crate, and a removable crane (together with a prop so the suspension doesn't compress when the crane is loaded up!). The rear bar fits in a pair of sockets welded through the tray floor, in to which also fit anything else I can mount on a piece of square RHS, for example a vice for chainsaw sharpening etc..

Because I have a bad back, I also have my trays built to a length at which I can easily hook a trailer on to the tow-bar - I've seen some trays that extend way past the tow-bar meaning you have to reach underneath or bend and contort, and I'm too old and knackered for that!