The best to get from one end of the trailer to the other is use the Air Conditioner ducts. Just pull down each register which are about every six feet or and fish your Video cables thru each one to the next one.
I ran all kinds of RG cables for my two way radio setups in my trailer doing this. When you get close to where you want to go you may have to punch a path thru to come out inside a ceiling mounted cabinet or something but worked out great for me. Any hole I made I sprayed expanding foam into them after I ran my cables. Did not hurt the air conditioning at all...
Roy Ken