I was able to solve my extension tube problems with the help from Michael from Bintel Sydney(thankyou)
I brought a cheapo 3x barlow and with it a 2" extension tube. See photo's.
As you can see it gives me about 150mm extension tube which I need to get inside and outside foucus for collimating.
So the 3x Barlow is long, take the lens out, bingo extension tube.
