SAP has not provided any configuration regarding using external number range for this otherwise you can use that.
Not sure if you are intrested in customized solution.
If yes here is the answer
step1: Create 2 number range object for each gate through SNRO
Step 2: Create a Ztable with following fields
Original leci number
Gate
New number range based on object type
year
step 3: update this z table with leci event using bapi NUMBER_GET_NEXT, (you can club updation of this z table with leci event.(change , create , insert, delete , modify, update ..... refer leci bapi) or a customised transaction with leci as first step and table updation as second step
Step 4: report it referencing ztable
LECI_EVENT
LECI_EVENT_DATA