Unless you're still a Student Pilot, you don't need an instructor along to log some simulated instrument time under the hood like that -- just another Private Pilot (or better) with the appropriate category/class ratings (i.e., ASEL) and a medical valid as Third Class (or better).
That said, make sure you do it by getting a lesson with an instructor, and then practicing what you learned with a safety pilot. I've had to undo the damage done by folks trying to get ahead of the game by teaching themselves instrument flying before coming to me for the 15 hours of instrument training, and that doesn't work well. I end up spending even more time breaking them of bad habits and poor procedures before I can teach them how to do things effectively and safely than I would have spent teaching them good habits and procedures in the first place.
Just make sure you actually land somewhere more than 50nm away on each of those IR training flights if you want them to count for that XC PIC time. A T&G is enough (even at night, unless you also want it to count for night landing currency), but a low/missed approach isn't enough for this purpose.