Would it be feasible to use an alternate client?

Don't see why not- As long as the client understands the communication to and from the server, and can understand the world file. It would need to be custom built.

I'm in the process of trying to build a Panda3D client. Still in the very early stages (converting the Network source code into Panda3D structured Python). I'll do a separate post once I get something working network wise.