I would say he should be very hungry. Also the pros don't use any other people during the training. And you're right about no dogs too. They normally start under a canopy of trees. Part of it is predators. Actually you want him to stay in the tree when he's there and wait for your call.
Try parrot recall training on yahoo, hugh choi. He's very nice and not quite as ADAMANT about super strict weight management. There are many experienced people there. One guy who has a show where they fly through fire. He's very adamant and people get mad at him but I believe it's important to hear the WHOLE communitys cautions and advise on such an important topic.
Hugh (and the fire guy too) has trained alot of humans on how to do recall ,,,meaning the steps in progression. I never really paid alot of attention to the distances when beginners start since I had no intentions of recalling Piper outdoors. But Peanut is small and a gust could get him off point so having an experienced trainer might smooth the way. Hugh is not at all condescending or pushy and you'll like him. Also he posts like you, short and sweet unless it's important
This is him:
theotiseffect.com - an urban tail
His birds are Red Fronts and go all over the US ....
He may have a better idea like going to a place where there is absolutely NOwhere to risk an overnighter but without predators is really really really important (i know you know lol).