How to keep shbbos when there is no sunset in norway?

ב"ה Shalom, This is a very complex question and there are indeed Rabbis who say to stay away from such places because of the problems that arise from this issue unless necessary. [See: תשובות זכר שמחה סי' ל, תשובות והנהגות כרך א סימן שטו, שו"ת דבר חברון ד' חלקי שו"ע סי' ס עמ' כ"ו] I will not take a personal stand on this issue, but I will present a few opinions. 1. The Star K Kashrut organization has a very detailed answer on this issue https://www.star-k.org/articles/kashrus-kurrents/515/when-does-one-pray-when-there-is-no-day/#f2 2. In the sefer Piskei Teshuvot Siman 344:4 . they quote a few opinions and then recommend one . They quote the opinion of Rav Yaakov Emden, the Mor U’kzia which is similar to that of the Tiferet Yisrael on Berachot Chapter 1:3, that upon arrival the person should count 6 days of 24 hours and make Shabbat on the 7th day as the gemara stipulates for someone in the desert who lost track of time. However, this can create a situation that a few Jews coming there at different times would observe Shabbat at different times, 3. Therefore, some say that they should consider the time when the sun is closest to the east as sunrise. Meaning they according to the latitude where they are they should follow it to the closest place where there is sunrise and sunset. 4. Others say, that one should take in Shabbat according to the time in Jerusalem from where the world was created and tis first Shabbat was sanctified there. 5. As aforementioned, the Piskei Teshuvot says that most Rabbis say to follow the opinion of the Mor U’kzia, that upon arrival the person should count 6 days of 24 hours and make Shabbat on the 7th day as the Gemara stipulates for someone in the desert who has lost track of time. 6. On the Chabad= Lubavitch website,for Oslo, Norway I saw that this upcoming Shabbat, Parshat Balak, begins at 21:57 =9:57 PM and ends on Sunday, July 21 at 17 minutes after midnight Saturday night. All the best