A 15mm 3/8" sq drive socket, a 3/8"M to 1/4"F reducer adapter and a 1/4" sq drive flex handle should give you a relatively light combination tool with enough "stand off" to clear the various obstructions. Add a short 1/4" sq drive extension if needed. The tool could be lighter still if you can find a 1/4" sq drive 15 mm socket but I don't think sockets that large are available in 1/4" drive.

All of these parts can be bought super cheap at any flea market that has vendors selling "Made in China" tools and they will be plenty durable for the use you intend.