Interruption power supply in V8

Hello, everybody.

I need you as a think tank ...

My long version is only very sporadically moved in winter. Currently the battery seems to be quite "platt", although I have already charged it 2x over an external charger during the winter. The problem is that I unfortunately have no power connection in the corresponding garage to connect it more frequently or permanently to the charger (CTEK). The battery (Original Audi - 105 Ah) is just a little more than 3 years old and has to be replaced as it looks.

==References== Problem has given me a forum song once an idea with the way to completely separate the battery from the on-board grid during the service life. Of course, this would involve some circumstances (radio code, BC, clock, etc.).

My question now is this:
If I could live with the restrictions as described above, how would it be easiest to separate from the grid? I'd like to do it through a hidden switch somehow. My V8 should remain as original as possible and the change should also be retrofittable. Please bear in mind that the battery under the e-back seats is very difficult to access and I'm rather not trying to change here. The solution should already be "practical" without first flogging around in the engine compartment or even using tools before starting.

What are your ideas on this subject?

Thank you in advance ...

P.S. The issue of anti-theft plays a subordinate role in my considerations!