I do something similar to this for Global Opinion Panels (Synovate). I send them my Victorias Secret bill, and any other materials I get from VS monthly. I cross out any info before sending the bill to them - usually just my account number. Since I've been a member of Global for years, I trust them and do not mind sending the information to them.
I got curious about SBKC & went to look around their website. I also did not see anything that said exactly what rewards they give you for doing this, but you can email them about it. The email for consumers is:
consumers@sbkcenter.com, or if you rather call them the # is: 312-546-4922.
If you're really interested in doing this, I would contact them and ask them exactly what the rewards are and also if you can cross out any information that you do not feel comfortable leaving on the stuff you send them.
I was also curious who told you what types of mail they wanted you to send them. The reason why I'm asking is because you listed credit card applications & auto insurance applications but that is not listed on their website. This is what is listed under the consumer panel as to what types of mail they want sent:
Insurance: Disability, Health, Life, Long Term Care, Medicare Supplement, Medicare Advantage, Medicare Part D, Prescription Drug Plans
Investments: Annuities, IRA/Rollovers, Mutual Funds, 401(k), Pensions
They also have the following listed on the Consumer Panelist page:
We are not looking for catalogs, magazines, credit card solicitations, telecommunications or the masses of other unrelated/unsolicited junk you surely receive.
They do have Auto listed as one of the materials needed if you become a member of their Producer Panelist, but not the Consumer Panelist.
I also wanted to let you know that they do have a place on their website to sign up. If you click on the tab that says Consumer Panelist, that brings you to the page that tells you about that panel and the form to sign up is on the bottom of that page. The same goes for the Producer Panelist page.
I just wanted to try to help you a little with this so I did a bit of looking around on their site. In the end though, if you do not feel comfortable with sending them some of the information that they are requesting, then listen to your heart and don't do it. Like I said before, you can always contact them & ask if you can cross out some of the information that is listed on the applications before you mail them. Who knows, maybe they'll say that it's ok.
HTH.