@DanSieg
Hi Dan,
First, I would ask if you have a personal banking relationship? If you do good, if not this is very important part of your finances and you need to have a seasoned checking account open. You also need to have your credit files good(the bank may not pull your credit just to get a letter, but will after you actually apply for a loan). If you have derogative credit you need to work on clearing this. Make 2015 the year to get your credit good. Never charge your CC beyond 30-50% of the credit limit.
So, assuming you do have this good already.
Give the banks mortgage department a call, introduce yourself. Let them know you are a investor in the area seeking investor loans.. and ask them what they will need from you before you visit the loan department.
Then go to your bank and talk to the loan manager and let them get to know you and build some rapport( talk about the real estate markets and try not to engage in general unrelated small talk). They will want a PFS so have your assets and liabilities on paper before hand. Reiterate you are seeking an investor loan pre-qualification and wish to establish a lender relationship. It very well could be they will type you a letter while you wait. Have your paper work with you and forms you use. Let them see you with your folders and paper work(property inspections, comps,etc.) Don't go in there and try to answer the questions pulling this info off of the top of your head. You will look unprepared.
Don't tell the loan officer you are wholesaling. Answer any questions directly and short. Lastly, do not lie. Hopefully you get a letter to present to the seller.
Think like an investor always.