Ok, I thought I'd send you guys an update, after a test which didn't turn out so well, I decided to take the easy way out and went out and ordered an ice cream cake. I was happy with it, although I know the Mickey Mouse face would have been cuter.
I'm still looking to see after I whipped up the Rich's Frozen Non dairy whipped topping, do I add something to it to make it sweeter? It tasted kinda bland for the top of the ice cream like it needed some sweetness.
I'm going to keep trying this and as soon as I can get an ice cream cake made with a character pan, I'll be sure to post the pics.
Thanks to everyone for help.