I hear you about the moving rigamarole. I do the same thing and recently couldn't take it any more and planted a mom outside. (I had up potted and she was just to heavy when wet and I was one wrong step away from trashing my back hauling her in and out.) She was down to about 14.5 hours anyway, so crossing my fingers. Next time around you should start slowly reducing your light schedule as soon as you purchase your clones, so by the time you transition your plants outdoors it will match the natural photoperiod.
There's nothing magical about the 18/6 schedule. I took about 20 clones off a plant about 3 weeks ago and put them under 15 hours instead of the 18 (or 24). Maybe took a day or 2 longer to root (10-12 days), but they're all outside now. There's various things you can try; reducing your light down incrementally, giving them extra light outside with a porch light for a few hours, or light striking for a shorter period, after a dark period. It's really the total uninterrupted period of dark time as opposed to the total light time (and why indoor growers are super anal about making sure they don't get any light leaks during lights off.) As I mentioned, it doesn't need to be a grow light (just slightly more than a full moon). Indica's are a little more fussy then the sativa, but it's always somewhat of a crap shot. (We've been having shit weather for the last week, so I'm sure the evening and morning light isn't as good as a sunny day. And it's suppose to rain this weekend, so if you're up north, I'd try to keep plugging away with your moving for another week or so.)
If you've been giving them daily sun, they're already hardened off, so they'll be fine when you move them out permanently. Nothing wrong with neem & silicate, but that's a very aggressive schedule and you should reduce you're spraying down to every other week or so (unless you're trying to cure a specific problem.) It's fairly easy to burn the plants with neem, so might be why you got some burn.