Over the Hills and Far Away is a regimental campaign game from the fertile gaming mind of Jim Wallman.
Strange Aeons is a commerical rules set, but if you already own it, you may be interested in these free modifications for playing in an 18th Century setting.
Here’s a website with lots of information on smuggling in Britain in the 18th Century. I think there’s lots of gaming potential here.
Pendraken offers The Wolf Who Would Eat The Lion, a set of free wargames rules for 18th Century Warfare.
Seven Years Warmaster is an adaptation of Games Workshop’s Warmaster rules for the Seven Years War.