Also, if that's the module (the box) you're planning on using, it's a Type I and is missing the truck frame. Therefore, I assume you're planning on building a trailer frame for it to sit on. In that case, your options are endless and basically all you would need is two straight rails made out of large channel, which can extend out the front as far as you want it to, before forming the triangle.
If angle of attack and departure are your concerns, you're probably barking up the wrong tree to start with. This type of body is more suitable for basic flat terrain due to the overhang created by the compartments.
I have also seen these bodies mounted on a flatbed trailer with no sides. The wheel well flares were removed and a square plate used to cover the openings with a door for access. This creates two compartments that can be used for dirty or wet items. The hollow space underneath the middle can be made into a very long storage area or used for mounting battery banks, water and sewage tanks, awning poles, etc. Access doors can be installed at the front and rear of the body.
If the trailer is longer than the module body, you can even have a small deck at the rear!
