Defoliation (no horizontal room in my tent and a lot of vertical room)

Skirting or "lollipoping" your plants won't really push more vertical growth but I'd say your plants are on pace. Remember when you switch to 12/12 you're gonna get plenty vertical growth during the stretch of early flower, they'll likely double or even triple in height. I would probably recommend skirting right before you change to 12/12. If you plan to remove it anyway there's no sense in letting the plants waste energy budding out those areas.