This sounds like a recipe for getting scratched!!

I guess I will have to do it though & hope that she has claws b/c keeping her inside just isn't a viable option for us.
I would not worry about checking for claws if she is still afraid of you, you might get scratched. Give it some more time. If she is coming out for you and letting you pet her then once you feel comfortable you can check. If you do not plan to bring her inside, it is really a moot point if she has claws or not, right? Why risk scaring her off?
If she is hiding under your porch and getting to know you she will be fine for the short term. You need to gain her trust and get her to a vet, so take your time with it, the vet can also tell you the claw situation--also if she is male or female (I assume we don't know, but just using she since we are shes?

) and you would consider getting her fixed so that she does not have kittens under your porch come spring!
Our cat is an inside cat and she has claws, so it is possible this cat, if from a home does. Personally, I feel de-clawing a cat is inhumane as it is super painful for the animal. Most ASPCA or shelter cats if you adopt require you to keep the claws on as part of the adoption.
Any luck with the fliers? Our cat also has a micro-chip, so again, gaining her trust and getting her to go with you to the vet is the main goal. Could take a month or so with cats, be patient.
Hope this helps.
Amanda