Not tricky at all. Do same thing you would do for any other three phase system, and line to line loads - there is no line to neutral loads in this system.
If you have multiple single phase loads of same rating put 1/3 of them from A-B, 1/3, B-C and 1/3, C-A. Doesn't matter if grounded phase is run through breakers or not, that is how loads need connected to balance the load. If you tie every load to grounded phase it will have more load on it than the other two phases should be about 1.73 times more load - it is not a neutral and doesn't carry imbalanced current like a neutral in a three wire single phase source.
Would it make a difference if the system was derived from two single phase transformers as an open delta?