I think you are trying to say that you found a tent. Am I right? Or maybe you already knew the tent was there. But your point is that there was a tent there, and you didn't stop and put up a tent yourself.
This is what you must explain. "There had already been a tent" does not work because it says there was a tent there once, but it does not say that it was still there when you needed it. If I was on a glacier, cold, needing shelter, it would do me no good if there had already been a tent there in the past. Maybe there was a tent there five years ago but it was gone. That wouldn't help me.
I think you want to say "there already was a tent" but you will have to explain why it was there.
I found it. I couldn't know it was there, I just fell there(and got hurt, but if I pasted the whole story, it got deleted...)
Then I have to say: There already had been a tent, when I fell on that glacier?
I'm told to use the word tent, and I couldn't figure out anything else right now.
So, I had better not use Past Perfect?