Some FRP questions (joining, securing, glueing, etc)

On my 6'8" wide x 10' long x 7' tall camper build I am going to use 4x8 sheets of FRP from Lowes as the covering. I have read many threads on FRP but still could use some help as it relates to my build. I would like to do things as easy/simple as possible.
1. How do you recommend I transition from one sheet to another? I.E. each side will require two sheets that will require some type of covering where they meet.
2. What type of trim should I use to cover the corners of the sides and the roof?
3. How should I seal the FRP where it joins the doors/windows?
4. For a trailer this size, what is the needed backing for the FRP? I.E. 1/4" ply, luan, osb, or none at all?
5. What is the easiest method to secure the FRP to the backing identified in #4?
Thank you for your help!
1. How do you recommend I transition from one sheet to another? I.E. each side will require two sheets that will require some type of covering where they meet.
2. What type of trim should I use to cover the corners of the sides and the roof?
3. How should I seal the FRP where it joins the doors/windows?
4. For a trailer this size, what is the needed backing for the FRP? I.E. 1/4" ply, luan, osb, or none at all?
5. What is the easiest method to secure the FRP to the backing identified in #4?
Thank you for your help!