IRule for reverse proxy with http rewrite

Well, technically you cannot perform an HTTP redirect and be transparent to the client. The very nature of an HTTP redirect involves the client. In order to be transparent, and perhaps the only way, is to (reverse) proxy access to that external site through your F5. You would define that external site as either a node or its own pool. Then you could do something like this:

when CLIENT_ACCEPTED {
    set default_pool [LB::server pool]
}
when HTTP_REQUEST {
    switch [string tolower [HTTP::uri]] {
        "/jobs/apply" {
            HTTP::uri "/apply"
            pool newsite-pool
        }
        "/jobs/apply/resume-thanks" {
            HTTP::uri "/thankyou"
            pool newsite-pool
        }
        "/jobs/privacy" {
            HTTP::uri "/privacy"
            pool newsite-pool
        }
        "/jobs/terms" {
            HTTP::uri "/terms"
            pool newsite-pool
        }
        default {
            pool $default_pool
        }
    }
}

You'll probably also want to have a OneConnect profile applied to the VIP.