ふくろうのストレスにならないように、見たり写真を撮ったりするのは午後6時までにしています。 NHK
So as not to cause stress to the owls it has been decided that viewing and taking pictures will be until 6 o'clock.
Not even certain I've translated this correctly. It feels like there is something missing. To my non-native brain, at least, it seems like it's lacking a potential form or some kind of expression of 'only'. Maybe 見たり写真を撮ったりできるのは6時までにしています.
I'd really like to add an 'only' as well: 見たり写真を撮ったりできるのは6時だけまでにしています. But then I started to wonder whether it should be までだけ or だけまで or whether they are both unnatural.
Could you please comment on the naturalness of all these variations of the sentence?