To be honest, the mantra to "only cosplay someone who matches your physical traits" doesn't really hold up well in many cases. It shouldn't matter what your physically. I've seen short Sephiroths, tall clouds, short dantes and tall Neros. It doesn't matter. If you can pull off a character, or want to cosplay a character, go for it!
As for Trish, if you really want to cosplay her, go for it!
Don't meddle in the affairs of dragons, for they think you are crunchy and good with ketchup.
Current Cosplay Project:
Nero- Devil May Cry 4.
Current Costume status: Wig ordered.
Current Prop status:
Deathbringer: Full scale mock-up 85% complete. Design adjustments in progress.
Red Queen: Design in progress
Blue Rose: Not started yet.