Nope, no good. It has to be a bank or brokerage account statement. I know of no online wallet services that offer monthly statements - because as you point out, the blockchain has the evidence of what the account balance is, making official account statement preperation obsolete. But try to tell that to the regulators in the SEC.
First of all you don't send anything to the SEC. While the SEC is the regulatory they leave it to the issuer to handle accredited verification. I mean it isn't like bank statements or brokerage reports are cryptographically secure, so the burden of proof isn't that high. The issuer just need to "check the box", to show they made a good faith effort to validate the person and screened out non-accredited investors.
Have you asked the trust if they will consider Bitcoin wealth towards the accreditation threshold? In most cases dealing with a broker who has never heard of Bitcoins it probably is a long shot but this is the Bitcoin Trust. Now if they won't accept a particular proof of net worth then you are out of luck it is up to each issuer and there is no appeals process, however all wealth counts towards the threshold for accredited status. Many people own land, shares in other privately held companies, convertible notes, bullion reserves, real estate (but not primary residence), royalty contracts, etc and are can show accredited status. Wealth it wealth. Really the issuer is just looking for cover their ass and show an auditor they are open to the public.
