With lights always test by using the back of your hand and bring them close as possible, if it burns you in 10 seconds it's most likely going to burn your plants but if it's just warm up a ok
Honestly, whatever think you have room for, keep temps down...maybe go and get some reflectors, I bought mine at Walmart for $4 it's like a hood you would see in a garage, has a clamp on thevhand, very easy to hang....u could even go to lowes and pick up some cheap y splitters and change all those bulbs you have already hanging into double!