How about this one graham?
http://www.teleskop-express.de/shop/...r-Astroph.html
not sure if it would effect the ability to reach focus - that is a lot of spacing.
for the newt I would recommend the baader Rowe Coma Corrector.
http://www.teleskop-express.de/shop/...-distance.html
best of luck,
cheers