I'm not aware of DBIx::Class being able to send queries to Solr, for example

It looks like it does to me:

DBIx::Class::Indexer::WebService::Solr

Even if it dosen't do exactly what you want, personally I'd rather take that and modify it to get it to do what I want instead of start from scratch.

As I've said, the model I'm working on is above any db layer.

Its your project so you know and I don't, but since you're here asking for advice I'll give it: DBIx::Class works above the db layer. From here it looks like you are reinventing wheels instead of figuring out how to add in hooks to existing frameworks.