Rather then a full length fly line, you might consider a mono running line with a OPST Commando head and a poly or versa leader to achieve the depth you want to swing.
The OPST guys are located in Tukwila and can answer what questions you might have.
I know a few people that are using this combo on their single handed rods and like them.
Any of the local fly shops can help you as well.

No disrespect to Nick, but I'm done with Rio lines until they do something about their durability. Too bad because I really like their tapers.
Airflo and SA are much more durable lines in my opinion.
Good luck,
Go Dawgs!
Founding Member - 2021 Pink Plague Opposition Party