If you are careful with a the cable ends, and hopefully have a 2nd set of hands to assist, it should work just fine. The battery settings savers are not that expensive, I think you can get one that uses a 9-volt battery and plugs into the cig lighter socket for less than $20.00. One note, if you only have a 12v power outlet, and not a constant on outlet, it won't work because the circuit to it is shut off when the key is turned off.

My wife has an X5, with the battery in the trunk area, under the spare and air suspension pump system. It can take 20-30 min to swap that battery out, and the terminals are not easy to access. Fortunately, BMW designed a set of battery terminals in side the engine compartment, so when I had to change the battery, I connected a spare to these terminals before removing the rear battery, and all was saved.