Wow, you're really diving deep into the experimental stuff :-)
You've got the config right, the only setting you don't show is <add key="SubSonicProvider" value="subsonicSQLite" />
I think the problem is a bug/regression in my SQLiteMonoDataProvider.cs. Its not included in the main solution, only the precompiled SubSonic.dll is there, but if you checkout https://forgesvn1.novell.com/svn/mojoportal/vendor/SubSonic in a separate folder and change the reference from the dll to a project reference with the SubSonic.csproj you can step through the code. I will do this myself when I get a chance but mentioning it in case you don't want to wait.
The reason I think there is a bug in the provider is recently there was a bug in the links module for Sqlite and I had to back out the use of SubSonic there though it was previously working. I just haven't had a chance to look into it and I have other more pressing priorities at the moment.