I have a similar setup at my house. The return line is plumbed into the tank drain valve, which provides recirculation and instant hot water at the far end of the house. I modified the attachment of this line to the bottom of the heater so I can attach a hose at the bottom of the tank and flush out the sediment. This works pretty well.
You could plumb one of these in, see hot water filter on bottom of page.
PlumbingSupply.com - replacement water filters for hot and cold water
You could make a simple filter by adding a vertical leg to a horizontal run. Sediment will fall into the leg, which you can clean by taking off the cap on the bottom (like a gas line sediment trap).