Cool idea. Last year in December we had a WK community event taking the JLPT 2018. So in case you have any questions or need help feel free to let me know 
I took a very brief glance over the N5 vocabulary and grammar section and it looks like the JLPT Sensei Mock test (N5) is not the JLPT 2018. So durtles who took part in the community event and want to retry the same level can still do that, I think.
As for study buddies I’d like to recommend the The JLPT 2021 thread as well.
Unfortunately this is not possible do to the novelization of the test structure. Instead of a weights based system the test results will based on the individual answering pattern.
But last year @rwesterhof senpai did an amazing job calculating some weight assignments for 2018 N5. Maybe you guys feel like doing something similar for the upcoming mock test (or maybe after…) to get an indication if you’d have passed or not.