How much do these fixtures weigh?
I have in the past (with great results) used these lags, They are a combo used by pipe fitters and the like.
They are a lag on one end and a trhreaded rod coupling on the other, They are designed to lag into a wood joist and attach threaded rod to the other end.
Some lock nuts and and another rod coupling. Sometimes you will need to make an offset in the rod to get it right.
One rod usualy works, but if their heavey, use two.
This is quick and simple, And lags can hold a good deal of weight.