first of all, how good of a gardener can you be with one hand?
just kidding. ask away.
romaine grows quickly in the right temps and soil, so getting a small head isn't difficult. but ya gotta start early. i usually overplant, putting a whole seed packet or more into 2 rows on the same long mound, 12 feet long, with the rows spaced about 16 inches apart. the trick is to not plant the seeds too deep, just barely covered with soil. and keep them good and moist without washing them away for about a week until you seed the tiny plants breaking the surface. making the rows slightly indented into the long mound before seeding helps accomplish this.
i will harvest the whole small plants as they grow, leaving the increasingly spaced other heads to come to more maturity, eventually getting decent heads.
as the weather warms, though, it'll become bitter and be attacked by bugs, and eventually bolt to seed, so pick as you need it.
hope this helps hb, and let my hand go already. my palm's getting sweaty...