You can do stress analysis with Xpress you are just limited with the options you can include. From what you are describing though it sounds like you may be able to get some results that would help you out.
As I recall, Xpress only allows you a very limited set of restraints, so your results are quite likely to be badly off if the allowed restraints don't match up well with the actual restraints. I thinkyou are also stuck analyzing one part at a time.
You will likely be forced to assume that the ends of your rollers are fixed, which is not a very good approximation to what really happens.
The one part at a time issue will make it very hard to analyze the whole system. And the minimum number of possible restraints may make it impossible to get good approximations for the behavior of the individual parts.