I just changed out our existing queen bed for a Tempurpedic king bed and we now have the same room on the trailer that we have in our home (where we spend 9.5 months of the year). We simply removed the two night stands, the two piece head board and the queen mattress metal support frame that sits on the wood base. I had ordered king replacement parts for these the previous month and the cost from a dealer including shipping was just under $700.
The only challenge, was that to get the larger metal mattress frame into the bedroom, it had to go through the bathroom, and to fit, we had to remove and then reinstall the toilet.
Now we are Happier Campers!
Next project: Adding disc brakes.
2012 36RE Purchased 8/11
2011 Ford F250D w/airbags