Floydian Theory

There really is no way to ensure how your "trip" will go.
Everybody has different body chemistry so drugs effect them in different ways. I personally wouldn't suggest using mushrooms for the reasons you mentioned.
Self-analysis and self-searching are processes that you really are better off having a clear head for, and I have read and been told numerous times that using drugs to try and enter these states can actually inhibit the process and possibly be dangerous. Basically, you can teach yourself ways to enter these states of higher being, and the more you use the same methods, the better those methods work.
So if you figure out how to enter said states, while using mushrooms, it will be much harder for you to enter those states again without the use of mushrooms.
I am not an expert but have done alot of reading, research, and have had many discussions about these types of things with friends. So this is just my advice, take it how you like.
P.S. Meditation is actually probably the best way to enter these higher states of self. But everyone is different about meditation. Find what works for you, and improve on it.
The trick is to find things that relax you the most.
Example; I use very quiet, melodic music in the background, I close my eyes, focus on my breathing and let the music take me along for a ride. I also use Nag Champa incense which has a very pleasant smell. The incense can help to let my subconscious know that I am ready to meditate.
It's kinda like when a woman who just had a baby, hears a baby cry, her breasts will leak the milk. It is kind of an associative thing.