Ted, I would think that if you bowhunt Texas you'd have a vested interest in the outcome of this Bill and could sign the petition.
You could further add the fact that the outcome in Texas will be used to support one side or the other during the decision making process in other States and you have a bigger right to sign.
The elected powers that be will certainly be more interested in their voter's signatures but I'm sure Texas Parks and Wildlife is interested in selling the non-resident license too.
I guess if you are a non-resident and wish to sign, you could do so but please disclose that you are a 'non-resident with an interest in this Bill' in the comments section of the petition so we can subtract those numbers and arrive at "resident total".