I speak Swedish quite well, but my active Norwegian is very basic, although I can understand most of it if I concentrate. I’m aware Norwegians can usually/always understand Swedish. I’m told Norwegians and Swedes may have conversations in which each speak their own language. I’ve seen exactly that in films, and I find it weird, for I understand one half of the conversation perfectly well, and the other half only partially and with difficulty.
When I visit a non-English speaking country, I tend to try to speak the local language, however basic. Personally, I find it arrogant or rude to expect the locals to speak a foreign language when I am the visitor, even when I’m in a country where the level of English is generally very high (such as in Norway). Not everybody is at ease speaking English, in particular in off-the-beaten-track rural corners of the country.
But how is it perceived to speak Swedish in Norway? May it be perceived as rude or arrogant to expect that everybody understands what is, after all, a foreign language? Or does the closeness between the languages mean that people likely wouldn’t think about it, and perhaps barely notice it? There may be cultural issues related to history that affect this as well.
In case it matters, consider a rural area of Trøndelag that receives relatively few foreign visitors.
I could either try to speak broken Norwegian with Swedish mixed in, Swedish, or English (or German, but I’ve only ever once come across a Norwegian Sami person where that ended up being our best shared language).