For a small to medium ISPs (especially WISPs) looking to move to IPv6 dual-stack, the right way to deploy is to use DHCPv6 prefix delegation. Here is an example of how to do this in-skin (i.e. on the mikrotik itself rather than a relay).
/ipv6 dhcp-server
add address-pool=vl100-v6-pd-pool interface=ether5.100 name=vl100-v6-pd
add address-pool=vl101-v6-pd-pool interface=ether3.101 name=vl101-v6-pd
add address-pool=vl102-v6-pd-pool interface=ether2.102 name=vl102-v6-pd
add address-pool=vl106-v6-pd-pool interface=ether1.106 name=vl106-v6-pd
add address-pool=vl108-v6-pd-pool interface=ether4.108 name=vl108-v6-pd
/ipv6 pool
add comment="VLAN103 IPv6 prefix delegation pool" name=vl103-v6-pd-pool prefix=2001:db8:1a:b000::/48 prefix-length=59
add comment="VLAN100 IPv6 prefix delegation pool" name=vl100-v6-pd-pool prefix=2001:db8:1a:8800::/48 prefix-length=59
add comment="VLAN101 IPv6 prefix delegation pool" name=vl101-v6-pd-pool prefix=2001:db8:1a:9000::/48 prefix-length=59
add comment="VLAN106 IPv6 prefix delegation pool" name=vl106-v6-pd-pool prefix=2001:db8:1a:9800::/48 prefix-length=59
add comment="VLAN108 IPv6 prefix delegation pool" name=vl108-v6-pd-pool prefix=2001:db8:1a:a000::/48 prefix-length=59
add comment="VLAN102 IPv6 prefix delegation pool" name=vl102-v6-pd-pool prefix=2001:db8:1a:a800::/48 prefix-length=59
/ipv6 address
add address=2001:db8:1a:103::1 disabled=yes interface=bridge.103
add address=2001:db8:1a:106::1 interface=ether1.106
add address=2001:db8:1a:102::1 interface=ether2.102
add address=2001:db8:1a:101::1 interface=ether3.101
add address=2001:db8:1a:108::1 interface=ether4.108
add address=2001:db8:1a:100::1 interface=ether5.100
add address=2001:db8:1a:ffff::1/128 advertise=no comment=loopback0 interface=loopback.0
add address=2001:db8:1a:fffe::2/127 advertise=no comment="point to point to tower1-gw" interface=ether7
Adjust firewall filters for IPv6 as policy dictates. Do not filter ICMP
/ipv6 firewall filter add action=accept chain=forward comment="Allow all IPv6"
/ipv6 nd
add interface=ether5.100 managed-address-configuration=yes other-configuration=yes
add interface=ether3.101 managed-address-configuration=yes other-configuration=yes
add interface=ether2.102 managed-address-configuration=yes other-configuration=yes
add interface=ether1.106 managed-address-configuration=yes other-configuration=yes
add interface=ether4.108 managed-address-configuration=yes other-configuration=yes
/ipv6 nd prefix
add autonomous=no disabled=yes interface=ether5.100
add autonomous=no disabled=yes interface=ether3.101
add autonomous=no disabled=yes interface=ether2.102
add autonomous=no disabled=yes interface=ether1.106
add autonomous=no disabled=yes interface=ether4.108
/ipv6 route
add comment="IPv6 Default Route for static deployments" distance=1 gateway=fe80::2a7:42ff:fe2d:3574%bridge.10
Tunable based on deployment model
/ipv6 settings
set max-neighbor-entries=1024