Dave,
Betty and I are also so sorry to hear of Sharon's passing. We know this has to be devastating.
As for the trailer, Steve is right ... our hitch is rated at only 5K. Years ago, I had a welder in Bend crawl under the coach and weld up the hitch to the frame. At the time, he indicated that with the gussets he welded in, the hitch could easily surpass 10K lbs. With the C12, power was not a concern but breaking capability was ... but that had never appeared to be an issue over the 10 to 15k miles we towed a 10K pound ... 20 ft ... utility trailer (with our Mini Cooper and other stuff inside). We rolled it over scales in Oregon one time and it weighed out at about 7800 lbs. With the 10 to 15K miles we towed, we never had any hitch issues, so I think I would have a welder take a look at strengthening the hitch and you should be fine.
Again, we are so sorry to hear of Sharon's passing.
Glenn and Betty Perkins