Hmmmm.Lowryder only grows no more than 2ft in height. You're out of height space already? Are you 100% sure it's LR?

If they get too big and you just, let them go, they will start touching the grow bulb and the top buds/leaves will burn. Not a good idea.

Tie your main branch down, just by gently bending the top cola slightly. That's your best bet, or get more head room.

Good luck.