Monitor a Client that connects to a vip

it might be me but you seems to mixing the term monitor here, are you talking about a health monitor to determine if the pool member is up?

in that case you might want to use an inband monitor, it will check the client traffic and if that fails the pool member is marked as down. it won't detect failures before actual client traffic is seen but it feels like an option.

https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/ltm-monitors-reference-11-6-0/1.html