Dumbells helped with my squatting depth...after I tried a normal "ass-deep" barbell squat with lowered weight. Ugh!
 Dumbbells kinda cumbersome and get in the way a bit, but I'll try to manage. 
The issue with my back is, I have few fused vertebrae, and flexibility is a problem, ie trying to keep a neutral back while pivoting at the hips past thighs-parallel. 
Having the weight below my centre of gravity makes it easier, but my form if probably still compromised. 
Maybe front squats are the answer, eventually. 
However, I really feel it in the glutes and hammies more from going deeper, that's for sure!
Thanks Totz!