Is it possible to......

SS+ for 2 or 3 weeks and then do 2 weeks at 1000kcal at a time?

I know itll be hard going into ketosis again but is it allowed?

yeah probably! i don't see why not, just will be harder for you but yeah go for it xx

You would be missing out the 810 step, so its probably not a good idea.
Once you are on SS+ its best to stick to SS+ for as long as you need to. The first time you go on this diet is the golden time. Once you start messing about with the plan it gets harder.
There are alot of strugglers and restarters on this board (me included) who thought they would be ok to move off SS or SS+ and its backfired to a degree.
Have a chat to your CDC and see what he/she thinks.

Thanks spooky as always you are the words of wisdom!