Given that some RV's have problems out of the gate your first trip should be a shakedown cruise close to home. I wonder if you will be doing a thorough predelivery or will just rely on the salesman's assertions ( A BIG MISTAKE).
You do not know if the tires on the 5er are adequate for the job. (Yes they are new but some manufacturers put tires on that are so near the max load limit it is a disgrace).
There are other gotcha's that you need to know before you go.
At least find out if the selling dealer has a space with hookups you can use for a couple of days while you familiarize yourself with all the systems on the 5er.
I wish you luck and look forward to your reports on the road.