Packing Entities into a single MODBUS register

Configuration
1

I am a newbie to HA and I am looking for a bit of guidance on how best to approach gathering several HA bit entities and packing them into a single modbus register write.
A little background, I have a MODBUS I/O device which has 50 or so registers but the main 2 registers are the Status register which has the switch states packed into 1 word. And then we have the output states packed into another word.
I have worked out how to unpack the switch states using a template, see code below for SysStatus
I want to pack output LED data into the GreenLEDS register, there are 6 LEDS.
LED values are 0=off, 1=on, 2=slow flash, 3=fast flash
B0, B1 = LED1
B2, B3 = LED2
…

Any pointers would be appreciated
Thanks in advance, Richard


# Loads default set of integrations. Do not remove.
default_config:

# Load frontend themes from the themes folder
frontend:
  themes: !include_dir_merge_named themes

automation: !include automations.yaml
script: !include scripts.yaml
scene: !include scenes.yaml


modbus:
#Configure MODBUS connections
  - name: modbus_hub
    type: serial
    port: /dev/ttySC0
    baudrate: 9600
    bytesize: 8
    method: rtu
    parity: N
    stopbits: 1

    delay: 0
    message_wait_milliseconds: 5
    retries: 0
    timeout: 1

#Configure MODBUS entities
    sensors:
      - name: SysStatus
        slave: 99
        address: 21
        input_type: holding
        data_type: uint16
        scan_interval: 1
      - name: UpTime
        slave: 99
        address: 5
        input_type: holding
        data_type: uint64
        scan_interval: 1
      - name: RxCount
        slave: 99
        address: 9
        input_type: holding
        data_type: uint64
        scan_interval: 1
      - name: RedLEDs
        slave: 99
        address: 47
        input_type: holding
        data_type: uint16
      - name: GreenLEDs
        slave: 99
        address: 48
        input_type: holding
        data_type: uint16


# The following looks at the SysStatus register, and then creates several new entities with their own name
# so you can use them in your automation
sensor:      
  - platform: template
    sensors:
      sw1_pressed:
        friendly_name: "SW1 Pressed"
        value_template: '{% if states("sensor.sysstatus") | int | bitwise_and(1) %}  on {% else %} off {% endif %}'
      sw2_pressed:
        friendly_name: "SW2 Pressed"
        value_template: '{% if states("sensor.sysstatus") | int | bitwise_and(2) %}  on {% else %} off {% endif %}'
      sw3_pressed:
        friendly_name: "SW3 Pressed"
        value_template: '{% if states("sensor.sysstatus") | int | bitwise_and(4) %}  on {% else %} off {% endif %}'
      sw4_pressed:
        friendly_name: "SW4 Pressed"
        value_template: '{% if states("sensor.sysstatus") | int | bitwise_and(8) %}  on {% else %} off {% endif %}'
      sw5_pressed:
        friendly_name: "SW5 Pressed"
        value_template: '{% if states("sensor.sysstatus") | int | bitwise_and(16) %}  on {% else %} off {% endif %}'
      sw6_pressed:
        friendly_name: "SW6 Pressed"
        value_template: '{% if states("sensor.sysstatus") | int | bitwise_and(32) %}  on {% else %} off {% endif %}'