Well, I don't think I'm over-hydratated, I don't drink an extreme amount of water, I think about 1,5l - 2l each day.
Trying to play in the morning would be a good option, playing in the house isn't an option because I live with other people.
Anyway, I'm planning on making a box with insulation material to point my bell into (just like playing into a closet full of clothes, but more portable).
I'll have to try it out and then I can probably play some trumpet in the garage in the morgning (with the box).
Thanks for the comments guys!