Thanks. The Hobby King receiver weighs 13g according to this:
Whatever I get, weight has to be within the ranges specified below for trainers. Or I could calculate wing cubic loading of a model that flies slowly enough.
The Cessna 170 at the bottom of the page
weighs in at 86g and has a span of 24 inches. Assuming a wing area of 24 x 4 = 96 inches and the weight of 3 ounces, plugging it into the calculator below gives a cubic loading of 5.5 and wing loading of 4.5 oz per sq in / 13.5 oz per sq dm and it flies slowly. Keeping this cubic loading for my model should give the same sort of slow flight.
Cubic wing loading calculator