Frangipani trees

I have 2 established potted Frangipani trees,1.2 meters tall that I would like to transplant into Mother Earth.
My yard is small, I am only able to transplant them close to a side fence. My major concern is that the roots will invade pipes, as they can only be situated a maximum distance of 1.6 meters from the sewerage line. Other sites have recommended 2.5 - 3.5 meters as being the preferred distance. What do you say?