I thought you might be interested in some of the ideas I've had for an upcoming SYW campaign based on a grid of just 35 squares (7x5). It's a work in progress so I'm open to ideas and comment.
The campaign is turn based, with simple orders for simultaneous action, based around the amount of 'effort' committed to achieving certain objects of campaign activity, such as moving, scouting, screening etc. The campaign has a table set up for each of the 35 squares so that the players can 'choose their ground' to some degree. Much more here:
https://olicanalad.blogspot.com/2019/02/a-seven-years-war-grid-campaign.html