if you create a point you can constrain it, unless it is meshed, it can't be restrained.
I have seen someone use a remote load though to do something similar. you might want to try that out.
I tried a small trick you could try as well to see if it makes sense with your results
You can cut a small (extrude cut) cylinder within your cylinder across the entire length. It can go as small as you like and can manage (say 0.5mmD) while applying fixtures. Or else you could also split a small cylinder of the the same size, again across the entire length and constrain this.
I restricted all three translations by picking the cylindrical edges created from the cut. And I allowed for only radial expansion in another fixture by selecting the cylindrical face created by extrude cutting. Worked fine to give sensible results across the cylinder in all directions. The only discrepancy will be around the constrained edges and face which is quite small to begin with. You could also try the one with the split cylinder perhaps it can be more accurate.