The working distance may not be measured from the front of the lens, but from the camera sensor. If you subtract the length of the lens, do you come up with something close to the 35mm distance you measured? If so, then your assumption of needing increased working distance seem OK.
I'm guessing that you will need greater magnification in order to get better resolution, and to do that, the lens needs to be longer, so, to get the required distance from the stage, you may need another increase in working distance.
If I were in your position, I would let the vendor know what my requirements were re: resolution, distance from front of lens, etc., and let their engineers figure out the appropriate equipment. Saves having to reinvent the wheel every time.