You're VFR, I don't really care what your altitude is. Of course, I'm in a Class D so I don't have much in the way of separation responsibility with VFR traffic. I'll tell you about other people that may be in conflict with your flight path, don't hit them please.
And though "I'll call your base" isn't in the phraseology in the .65, "extend <pattern leg>" is. And if I say "extend downwind" without specifying for how long, it's essentially saying "I'll call your base." Otherwise you'd just be on a downwind for eternity.