The main issue with the list is the number of columns. You should consider changing from checkboxes to something else.
If you are using a list form, you will need to convert your for to be a full-fledged InfoPath form. Depending on how complex your form is, that shouldn't be too hard. You can still have the regular InfoPath form map to the SharePoint list bt some configuration is required.
If you use Qdabra's DBXL Web Service (sponsor of this site), you could probably do the SQL integration in a couple hours. The major time investment will be setting up the database tables and the mapping for your form. After that it's easy. Check out the free trial for on the Qdabra site for more info. Once you have the mapping configured, you can use the migration tool to import existing XML documents.
To export list data to a full fledged InfoPath form, you can use Qdabra's XLS to XML tool. A trial of this should also be available.
Hope this helps,