Design Help: Retry Message Processing With A Delay?

I am implementing the first Sql Service Broker use case in our Sql 2005 application, so forgive me if this is an obvious question. We will be using a service & queue to handle requests to download a batch of documents from a third party service. The basic workflow is:
A. Web client requests a document download.
B. Web application begins a conversation and sends a message requesting the download
C. DownloadService stored procedure retrieves the message and attempts the document download.
D. If the download fails, retry every 30 minutes up to max 5 attempts.

Other than (D), this is perfectly straightforward. I will describe the design I've come up with to retry after 30 minutes below. I would appreciate any suggestions on better ways to handle this within SSB.

My solution relies on a small state table:
create table MessageState ( ConversationHandle uniqueidentifier NOT NULL, RetryCount int NOT NULL, MessageBody varbinary(max) NOT NULL )The web client begins a conversation and submits a message. It does not end the conversation, but rather the InitiatorQueue has an activation procedure to end its side of the conversation after the DownloadService ends them, as described here http://blogs.msdn.com/remusrusanu/archive/2006/04/06/570578.aspx.


The DownloadService logic, in pseudo-code:
1. Use a typical loop to get conversation groups and receive messages
2. If message type = DownloadRequest
2a. Call a stored procedure to attempt the download
2b. If successful, end conversation
2c. If not successful, add entry to MessageState and BEGIN CONVERSATION TIMER with a 30 minute timeout
3. If message type = 'http://schemas.Microsoft.com/SQL/ServiceBroker/DialogTimer'
3a. Look up conversation handle in MessageState
3b. Recall original MessageBody
3c. Call a stored procedure to attempt the download
3d. If successful, delete MessageState row end conversation
3e. If not successful and no retries left, delete MessageState row and end conversation with error
3f. If not successful and retries remaining, increment MessaageState.RetryCount and BEGIN CONVERSATION TIMER with a 30 minute timeout

The main downside I see to this solution is a certain lack of transparency. After step (2c) or (3f), "select * from DownloadQueue" will no longer show the pending request, although you can find it in sys.conversation_endpoints.

Is there a better idiom to solve this type of problem in SSB?