I wouldn't bother asking your competitors! But that's still a creative idea. They are not your customer so you don't really care about them. And you dont' want to be responding to them either. Chart your own path based on customer focus.
User feedback is the best. Accelerators that I have seen ask for interviews/testing with at least 100 people. Think about the goals of the MVP. All product activities are not about the product. They are about learning from your customers. Learn what they want, what they care about. Dont' even bother iterating or tuning features until you get some feedback from them.
However, you asked about mentorship. While you can ask anyone to be a mentor, it is worth finding someone(s) who are experts in the areas where you need help. Do you have startup accelerators in your area? Many of them provide an entire network of mentors at your disposal. However, I live in Berkeley so I know not everyone may have that resource. FD (this site) of course is a great place to build those kind of relationships.
Cheers, and happy to help further.