Of course, as a wife you must seek to please your husband in all ways: beautifying ones self etc, but how do I do this when I’m strict with my hijab around non-mahram?

With Allah's unlimited grace, we try all we can to advice our brothers and sisters in faith and earnestly pray for the goodness of everyone and the society as a whole inshallah.
Islam is a perfectly balanced religion without any extremity or negligence and emphasizes that too.
You can request your future spouse if you can stay in another house nearby and mention the reason which is clear that living with nan mahram can be very difficult sometimes.
If he doesn't accept and has all the valid reasons, there is no dead end and you will still be able to practice your hijab and at the same time live up to your husband's expectations especially if you explain him of the limitations of living with a joint family. Taking to him beforehand will prepare his mind of what he will face.
You will of course have your private room to give the rights to your husband and beautify yourself too.
Near your extended family, you can be polite and respectful and wear simple clothing. Never get too close to.your brother in laws at the expense of your faith.
If he doesn't agree to this, then think carefully of the type of spouse you have selected before entering into marriage. Being a hauzawi, you must be aware of the values of our religion which only wants us to lead a perfect life, thus you must have a spouse who is compatible to your thinking and lifestyle also.
InshAllah Allah will help you go about this.