Do not trim, or you will shock them, resulting in a poorer yield. Bend them with ties. twine preferably. If you bend them over and they kind of break; Don’t worry about it; Just support them with twine from above.
Best to plan ahead when growing. Sounds like you should have started training them weeks ago, but you can manipulate them, even at this later date.
Drip irrigation. Good idea, but without knowing anything about your grow specifics; I cannot tell you how much you need. One thing I can tell you. You will need a big reservoir. Some flowering plants take a 1/2 gallon to a gallon of water or solution a day; So with 25 plants; You need a lot of solution in order to last 10 days.
So; Figure out how much your drip system is going to put out at each watering, and multiply that times the watering events, over 10 days. This should give you an idea. You have to know your system output. hope this helps