Hmm, coloring sounds reasonable then.
Are you actually doing a partial mash with that recipe? Or is the Caramel Malt being used in a steep? With an extract recipe I would suspect it is being steeped, although 49 ounces is quite a bit to just steep, so it might be a partial mash. Steeping is not that hard. 30-60 minutes, 150-170 degrees, sparge. Then again, a partial mash isn't that much harder as far as I can tell, but I have yet to do one ... and a partial mash would get more sugar out, which would be good for this and would add to the body. So, yah, I would go with the partial mash on this one. You want to get the sugars out if you are using that much Caramel Malt, is my hunch.
I assume you are planning Caramel 60L? Mmm, caramelly and good mouth feel.
I'm not sure which way you should go on this. I would consider sticking with all extract, but a little branching out won't hurt you - and it doesn't hurt to learn other things. It just gives up a bit of control, so you will have to watch it closer and decide if you have not messed up somewhere other than the alt-bitter. Good luck.