I don't see a problem here. It doesn't sound like you are overwatering, and a little droopiness is not a sign of imminent danger. They will droop a bit over night. As long as growth continues I wouldn't worry about it.

About your pot size: With flouros there is no need to go as big as 5gal (mind you it won't hurt) for a number of reasons, mainly because due to the flouros' lack of canopy penetration, you will not want to veg very long. Secondly, with Lowryder you can't veg very long anyway. Thirdly, you could use 1gal pots, fit more plants in the flower chamber, shorten the veg time, and get more weed. Also use less soil and nutes.