Ab, Everything I've read suggests only a few seconds between click and treat - never seen any mention of being able to extend the time interval and be sure the reward is still associated in animal's mind with the click. However, several people stress that the animal works for the click so reward every time is not essential and variable reinforcement schedules important too.

My pointer cannot take a treat when she has had lots of scent e.g. a point or even after the flush but I still click on occasions being confident that's a more timely/direct form of 'good girl' - something I did read somewhere in book/article on clicker training gundogs.

I think the distance click is maybe not such an issue. You just have to ensure something which can be seen or heard at a distance, whether light or whistle. The early 90s Hawk Chalk Pryor/Layman articles talk about this. So rewarding being at 1500 feet is probably not difficult (if indeed that's the right thing to do) but it's the act of climbing that needs rewarding. Traditionally falconers have simply served and waited longer each time. OC would suggest that clicking first would be more effective. What I don't fully get are the references made to 'keep going' cues i.e. is that a matter of clicking once during a prolonged activity, clicking many times, or having a cue which continues throughout. This is possibly relevant to some of the things you want to shape.

Re your circling over pond requirement, in those old articles, maybe Layman or Steve Martin, talks about shaping a hawk to not land when cast off the fist and also (I think I recall but maybe I'm dreaming) shaping a redtail to climb/wait on. This seemed initially to require just the immediate click and return for food that you mention but in the confidence that the hawk 'gets it' quickly and you can move on and extend the time the activity runs. By their approach you'd start like this and build up to longer flights. My fear would be that the hawk would stay flying longer each time but stay very close anticipating the click/reward but maybe that would just be a short-term problem and later you could start to click only when the bird goes out a bit. Presumably attaching a cue to all this would be important.

When you say 'stretch the time interval' if you mean extend the time interval of the activity then surely that's fine but if you mean extend the time interval between click and reward then surely you will weaken the association between the click and reward - accepting that variable reinforcement may be important anyway.