Too bad about over cooking the side dish. But, I hear ya. I've had the same thing happen using one of those huge bionic birds. Really cool the bird and rotisserie worked well though.
I'd thought about modding my cookers to take a rotisserie as well. But, during that thinking process, I'd put a whole bird on and was amazed at how well and evenly it cooked for me.
I'd reported that here on one of the many threads and another member noted (I forget who at this point), that "of course it would cook nicely because the pellet grills operate like a "convection" oven"
The more I thought about it more I saw that. They do move enough air that you can feel it coming out the vents on back. So, I abandoned thoughts of modding my grills.
Would be interesting now to see how it would work just putting the bird on the top rack, and either nothing under it, or something akin to what you did, (in my case I used a small 1/2 sheet pan nothing in it) under it on first shelf.
So would really like to see your thoughts and whether the rotisserie really made a better bird.
So that is your assignment, should you be captured the MI team will disavow all knowledge of you.
And now this post will go up in flames