HA Active/Standby add 2nd Floating IP from a different Vlan

Hi , 

To achieve your goal ,am thinking of two ways : 
1. creat a VS that has a node as 127.0.0.1 443 
you can use this kind of Irul : 
when CLIENT_ACCEPTED { node 127.0.0.1 443 }
I ve seen this method used for VPN access to GUI : 
https://my.f5.com/manage/s/article/K13299
depends of the version you may need to be aware of  :  
https://my.f5.com/manage/s/article/K05413010

2. create a new vlan or use an existing vlan and have in the floating IP address the portLockdown set to : Default .  
more info about the port lockdown feature : 
https://my.f5.com/manage/s/article/K17333

hope it helps   :)