I'm in the throws of rebuilding/upgrading my old 10" newt (f4.66) and it will go onto my New Atlux.
I'll also use my setup for imaging at prime focus with my 40D body as well as visual use.
I've used this model to calculate my upgraded OTA's design specs for astrographic and visual mode.
http://www.catseyecollimation.com/designie5.html
You'll need to make the necessary measurements of your OTA and input these to the model , it'll spit out the answers you need , which you can then examine .
You'll also need to know registry distance for your camera and how much your camera adapter plate adds to that).
You can then investigate what happens when you change focusor , and move the mirror up and essential play with the model to get the design you think will be your best compromise for multi-purposes.
In my case my minimum tube lengths are :
VISUAL USE length = 49.381in = 1253mm
Spider depth is 95mm (min) from front of OTA (can be shortened if needed by cutting threadbar length to suit).
PRIME FOCUS w/ MPCC ONLY length required = 48.746in = 1238mm
PRIME FOCUS w / Esyguider + Lumicon CCFF length required = 47.866in = 1216mm
I have opted to build my OTA to suit the astrograph mode with Esyguider attached to the camera body., and the Crayford racked in fully less maybe 3 to 5mm (my focusor has provision to adjust my racked in height if I need to).
If I decide to use juist the MFCC attached to the camera body - I'll not need to fully rack in.
When I'm jsut usng eyepieces , I expect to be able achieve focus ,if I need to have more focusor travel up ,I'll simply buy a 2" x 1" extension tube for those eyepieces.
I have made provision to move the mirror cell up an inch or so if I need it too (difference between the Esyguider mode and MFCC mode).
No you do not need to male you tube shorter, but you may need to move the primary closer to the secondary to achieve focus at the camera chip, if you don't have enough prime focus point placed in a range of draw tube travel that you can get with your current focusor.
Another solution is maybe to install second focusor at convenient point on the same circumference line as your existing focusor that has a very low profile , maybe a nice 2" helical (if money is tight) ..., then you simply rotate the secondary to poiut at the second focusor , collimate and insert the camera attached to the coma corrector (a Baader is probably the best for this available now (that Lumcon discontinued making there great 2" coma corrector (designed to be used with their 2" Newt Esyguider) .
I have a 2" helical focusor stashed somewhere if you are interested that I bought from Lumicon many years ago and never used..
If you can't reach focus on the camera with your existing OTA and focusor , then you either need a lower profile focusor and / or to move the mirror closer.