Some thoughts on session beers I have made and looking at Ron Pattinson's book of recipes, I will through this out.
Torrified what will help a little, but not American.
Flaked maize has been in many session beers I make.
Invert sugar has higher sugars, and seems to give a nice flavor and fullness to the beer if the toffee flavors are not overboard.
Most British session beers are in the 149 to 152F range in the mash, but that is for the British Pale ale Malts. The hotter NA malts may work fine at 158-160 and give the desired results.