I only started this a few weeks ago, so who am I to talk:
I'm currently doing a TGU with a 30kg dumbbell, which is the heavist dumbbell around. Hence, today I used a straight and quite short barbell and a curlbar to do the TGU, but balancing the weight was my main issue. The bar tilts back and forth and my wrist has very little power in comparison to the weights at each end.
Is using barbells (curlbar better?) the natural progession in this exercise? If yes, how do you balance the weight? I can't find any tutorial on this. There are no kettlebells in the gym. I can't move to the olympic barbells because the gym is not big enough to securely swing that thing around without smashing someone's head.
Did you use less weight at the beginning for the barbell, or is this only required while figuring out the balance issue?