I was wondering if anyone had any reccomendations for a paint or coating to put on the roof of my trailer to cool it down a little bit.  I have seen several online that are for RVs, but not sure what way to go and what is the best way to prep the roof for whatever I put on it.  TIA!

Take a look at Equine Kool. Its supposed to reduce the inside temp by 50 degrees. 

Since a LQ is basically an RV, with room for horses, I would just contact a good local RV repair shop and ask them.  They should know how to do it.  

There is a great document for this and many other projects on the FB group Horse Trailer Conversions II.  I used the information in this group to insulate my BP and now and using it to find information on redoing a new to me gooseneck. The document section is really helpful but I also just use the search bar to find old conversations for what I am looking for.