Composite Position without Datum References on Pattern of Parallel Cylinders as Primary Datum

Hi, I have a "carriage" part that glides on two ~Ø30mm ground shafts. Therefore, I'm wanting to use the pattern of two ~Ø30 cylinders of the part as the primary datum since they are the features that will constrain 2 Translation and 3 rotational degrees of freedom, with Datum B surface constraining the remaining axial translation.

I have put a composite position tolerance on the pattern of 2X Ø30 bores with the upper segment pattern-locating tolerance zone (PLTZ) with a tolerance of Ø1 and the lower segment feature relating tolerance zone as Ø0.065. The PLTZ is primarily intended to control the spacing between the two cylinders (Basic 50 dimension) and the FRTZ is to more tightly control the parallelism of the two cylinders. Both segments do not include datum references because this is the primary datum and no datums exist yet.

Do you all have experience with a primary datum setup like this? Is this easy to implement on CMM software? And what issues would you foresee with a datum structure like this?