[yukoncpa]

It helps to have these letters on the letterhead of an accountant who has had favorable experience in the past corresponding with the IRS. Most competent tax accountants should have plenty of experience writing letters on topics very similar to yours. I would have this letter reviewed, re-written, and signed by an accountant that you pay for. If your initial plan of attack is writing a letter, then I can’t imagine a CPA charging much. I would explain what you want over the phone and get an estimate.

edit - I deleted my original last paragraph. I really can't recommend doing this without competent review that you pay for.