Hi Michiel,
If you would like just 1 texture, you can use the style “Maximal Texture Count” and set “Maximal Texture Count” to “1”. The maximum size single texture you can make is 16k using this style. If you want to continue using your current unwrap parameters, you can increase the Maximal Texture Resolution to either 8K or 16k, and although it will still create several textures, it will be less than 50 textures. (17 x 8k or 5 x 16k)