I am stumped for an idea to go with this. Thanks for your help.

Cream cheese buttercream is what I would use. It's close enough to Italian Cream that I think it would be good. You can add extra pecans to it as well.
I have never made it but online there is a Browned Butter frosting that looks heavenly. That would be a nice compliment to butter pecan I would think.

Check these threads for some ideas:
http://cakecentral.com/cake-decorating-ftopict-612776.html
http://cakecentral.com/cake-decorating-ftopict-36634.html
also
http://www.cajun-recipes.com/html/dessert/1129.htm
http://www.yummly.com/recipe/Carrot-Cake-With-a-Pecan-Cream-Filling-Food_com-121873 (first 7 ingredients; click on read directions)
http://www.yummly.com/recipe/Praline-Cake-Filling-Recipezaar
http://cakecentral.com/recipe/bavarian-cream-filling

ButterPecan cake was one of my most often ordered and almost always w/bavarian cream filling.

Oooohhh! Bavarian Cream filling! Would you by any chance share the recipe? Also, to the OP, what recipe do you use for the Butter Pecan cake?