The Chesapeake is not "no discharge"
He can continue to use his Lectra/San there. However, there are a few "no discharge" harbors and marinas, so adding a small (10-15 gallon) holding tank is a good idea. There's just no reason to plumb the system to have the Lectra/San empty into it. Install a y-valve in the toilet discharge line that provides a choice between going through the Lectra/San or into the tank those few times when he'll have to.Tell him to get the tank from Ronco Plastics (link below)...they make top quality tanks and have more than 400 shapes and sizes to choose from, for a VERY reasonable price.I also suggest you either print out or give him the link to the Head Mistress forum reference library (link is on the forum homepage) to read before he starts this project.