As you say, nothing would prevent you from having only one such officer at each voting table. It would not cause additional problems. The only one that I can think of is this: how do you go about choosing or assigning these people? Do you continue to receive recommendations from the political parties or do you go and find them yourselves?
At the present time, the political parties make recommendations to you for the staffing of poll clerk and DRO positions based on the results they received in the last election in that riding. Right? If you had to recruit these officers yourselves, would that be a major problem for you?