Thank you all for your answers. I will soon buy a Vernet TT but until I do, I have found another TT I have and it may sound weird but, this one has a small slit in it, too. The slit is about three milimeters long but I thought I could use scissors to trim those three milimeters all around the tip, at the opening. This way, I wouldn't lose much loading space since the tip is loose on my thumb and I could perform fearlessly with it. Is this going to work or is it going to make it worse?
Oh and by the way David, sealing it with super glue unfortunately doesn't work.
Thanks in advance.

I had a tip I purposely slit for a certain effect. I used this for some time and then used it for various lit cigarette vanishes etc, The slit never got bigger, it only wore due to the heat etc. So you should not have a problem unless you overload it.

Well, thank you about that!
Oh and I did trim 3 milimiters down all around the opening of the tip and it worked like a charm! I then used a nail file to smooth the edges up.