I have mentioned a very effective print washer that used to be made by Arkay many years ago several times in the Forum. It consisted of a simple 11X14 tray with a lot of holes drilled in one end and a pipe with spray holes at the other. It could archivally wash RC prints in about 2 minutes. You could probably make one pretty easily. I recently found a replacement made by Doran Enterprises under the Premier brand. I got one from Photographers' Formulary, and I am now trying it out. The tray is oversized, so it will handle 11X14 prints easily, and you can probably wash more than one at a time. The washer is a bit more elaborate than the old one, and maybe not quite as effective, but it looks like it will do the job rapidly. Drain time is about 2 minutes. I haven't tested it for effectiveness, but you can probably fully wash an RC print or two in 5 minutes.
I have one of the old Arkay trays like you mention from the 60's, all enameled steel. It works fine, but with more than 2 or 3 prints in it, you have to tend it to keep them from sticking together, or if small prints, clumping up in the exit end. But it is a cheap solution.
I have a Arkay SS 16x20 version. I have not used it yet, does look like it will work fairly well.