I went the other way on our Rockwood. When we bought it in 2004, there was a fire at the oven thermostat plant that supplied all the RV oven manufacturers, so almost no trailers had ovens installed. A year after we bought the trailer oven/cooktops were again available and I removed our cooktop and replaced it with a cooktop/oven unit. The swap was super easy, the gas connection was in the same spot, only 4 screws needed to be removed to slide the cooktop out and then put the cooktop/oven in. Of course, I had to remove the doors and frame below the cooktop where the storage area was so the oven part would fit.
Make sure you don't throw away the brass adapter that the flare nut was screwed into. If I remember correctly, the new cooktop/oven didn't come with it, so I had to transfer it to the new unit. If you have to transfer the adapter, you will need some pipe joint compound or Teflon tape that is labeled for gas use.
Steve