gistfile1.txt

#The old ifupdown config 
# eth1_out was simply a routing table I added previously with the int value of 200

cat << ENIINTERFACE >> /etc/network/interfaces.d/eth1.cfg
# The ENI interface
auto eth1
iface eth1 inet static
 address 172.16.19.254
 netmask 255.255.252.0
 up ip route add default via 172.16.16.1 dev eth1 table eth1_out
 up ip rule add from 172.16.19.254/32 table eth1_out
 up ip rule add to 172.16.19.254/32 table eth1_out
 up ip route flush cache
ENIINTERFACE

# The netplan?

network:
  version: 2
  renderer: networkd
  ethernets:
    ens4:
      addresses:
        - 172.16.19.254/32
      routes:
        - to: 0.0.0.0/0
          via: 172.16.16.1
          from: 172.16.19.254
          table: 200
        - to: 172.16.19.254
          via: 0.0.0.0
          scope: link
          table: 200
      routing-policy:
        - from: 172.16.19.254
          table: 200


$ ip route show
default via 172.16.16.1 dev ens3 proto dhcp src 172.16.17.46 metric 100
172.16.16.0/22 dev ens3 proto kernel scope link src 172.16.17.46
172.16.16.1 dev ens3 proto dhcp scope link src 172.16.17.46 metric 100
192.168.200.0/24 dev docker0 proto kernel scope link src 192.168.200.1 linkdown

This works! I simply had to change the interface name to match mine!