Download selection of 500 customers

Hello,

We are rolling out CRM for a selection of countries. In our test system we want to download a selection of 500 customers for our users to test the system (rollout in 5 countries with 100 customes per country).

My question is where to define these 500 customers. In R3AC1 I can setup a filter with KNA1-KUNNR but maintaining this per range of 10 is quite time consuming. Is there an alternative of maybe a table behind this transaction that can be maintaned?

Thnx