webproxy and bandwidth control with queue tree

I have a Mikrotik machine 2.9.8 with two ethernet cards (Private and Public). This is the machine where I do nat (masquerade) and bandwidth control. I do bandwidth control with queue tree.

These are the rules for any customer:

/ ip firewall nat add chain=srcnat out-interface=Public src-address=10.132.243.33 dst-address=0.0.0.0/0
action=masquerade comment=“Node Poblado - Jose F Molina” disabled=no

/ ip firewall mangle add chain=prerouting src-address=10.132.243.33 action=mark-connection
new-connection-mark=JoseFMolina-con comment=“Node Poblado - Jose F Molina” disabled=no

/ ip firewall mangle add chain=prerouting connection-mark=JoseFMolina-con action=mark-packet
new-packet-mark=JoseFMolina comment=“” disabled=no

/ queue tree add name=“JoseFMolina-Download” parent=Private packet-mark=JoseFMolina limit-at=140000
queue=default priority=7 max-limit=160000 burst-limit=0 burst-threshold=0 burst-time=0s disabled=no

/ queue tree add name=“JoseFMolina-Upload” parent=Public packet-mark=JoseFMolina limit-at=140000
queue=default priority=7 max-limit=160000 burst-limit=0 burst-threshold=0 burst-time=0s disabled=no

If I enable Webproxy in transparent mode in that Mikrotik machine using the following rule:

ip firewall nat add in-interface=Private dst-port=80 protocol=tcp action=redirect to-ports=8080 chain=dstnat

the custmers don’t have any bandwidth limit when they are browsing the net.

If I want to limit the bandwidth of the customers when they browse the net, must I need to install an external Web-Proxy and use the following rule in the Mikrotik machine:

ip firewall nat add in-interface=Private dst-port=80 protocol=tcp action=redirect dst-address=ip-address-of-external-webproxy to-ports=8080 chain=dstnat ?

Or what else can I do ?

Any help will be apreciated.