Can Vlan tag checking disable on LTM?

that might be vlan source checking but I haven't set that up before so I'm not sure...maybe this will help? A drawing would help on my end to see what you're trying to accomplish, I think I'm missing something.

https://community.f5.com/t5/technical-forum/vlan-source-checking/m-p/255761#M239455

You could also look in the key database to see if something exists for that:

tmsh list sys db | grep vlan

This one looks promising:

sys db bcm56xxd.hgvlan_check_disable {