It's unlikely the boolean will result in better utilization, the savings will probably be consumed by padding. Most people don't know how to use structure packing to create a row which is actually smaller after it's been padded (though it's not very hard, anyone could learn). Columns are generally ordered by which features were shipped first and not by alignment (as is necessary to minimize padding).

I do try my best to pack my columns, but it's a fragile and likely premature optimization. Better to opt for something defensive at a cost of like, 7 bytes per row (in Postgres).