http domain redirect

you mean myhosts ? or myhost is an actual irule recognized command?

I do mean "myhost".

set myhost [class match -value [string tolower [HTTP::host]] equals myhosts]

set redirect 0
if { $myhost ne "" } { 
    set redirect 1 
} else {
    set myhost [HTTP::host]
}

If the class match returns a value and sets the myhost variable, then we simply set the redirect flag. Otherwise, we set the myhost variable to the actual host [HTTP::host]. In either case, the myhost variable contains a value in case the redirect flag is set and a redirect is issued.

Arguably option 2 will be the most difficult, given that your single data group may have MANY items to manage. Here's another option that combines options 1 and 3:

when HTTP_REQUEST {
    set myhost [class match -value [string tolower [HTTP::host]] starts_with myhosts]
    if { $myhost ne "" } {
        HTTP::redirect "http://${myhost}[HTTP::uri]"
    }

    set myuri [class match -value [string tolower [HTTP::uri]] starts_with myuris]
    if { $myuri ne "" } {
        HTTP::redirect "http://[HTTP::host]${myuri}"
    }
}

This will issue an initial redirect based on the host name, and then another based on the URI.