have you looked in to a fulltime nanny?? you can get the same rebates as ccc's as long as they are registered. he would then be at home or she/he could take him to kinder.
speak to the carers ask what he is like once you are gone...often they will stop crying shortly after you are gone.
is hea shedule type of boy? likes to know whats happening next??
we had one boy who his mum would tell him what time she was going to pick him up and all day he would ask what the time was(annoying for the carers but great for him) and he knew that it was getting closer.
other things to try
-would be not always dropping him of last ( if possible)
- try and time it that you and div get there the same ish time so you can walk in together a distraction from the beginning.
- maybe one day organise with the carers to read to the group so you stay for a good hour or so.

HTH