Large item storage at Hamburg airport

I am looking for reliable options for to store bulky items (specifically a child's car seat) at Hamburg airport, with long opening hours.

My family has decided to sell the car, as it isn't used enough to justify the expense and switching to carsharing services makes much more sense financially. In October we will be travelling, flying from Hamburg airport and returning there around a week later. Ideally I would like to drive us to and from the airport, leaving our daughter's child seat somewhere for the duration of our trip.

The only storage option I have been able to find on the airport website is the e-Shuttle counter near the check-in desks, but it seems to close at 21:00 and our return flight isn't due to arrive until 21:25. Add the time to get through passport control, collect luggage, etc, and we probably wouldn't reach the counter until over an hour after the indicated closing time.

Are there other options I've overlooked? My daughter is just about to turn 2 years old, so the car seat she needs is quite bulky; not just a booster that might be able to squeeze into a suitcase. We won't be driving at the destination so - while we can do so for free - it doesn't make much sense for us to take it with us.

We are aware that we can book a taxi with the appropriate car seat, but that's not our preferred option.

Are there other options I've overlooked?

Many parents have a folding stroller, with a removeable child seat that doubles as a car seat, with Isofix mountings.

You just unclip the seat, lift it into the car, clip it into the standard mountings that all modern cars have, and put the folded base into the boot. If the child is asleep, some parents will lift seat & child together into the car without rousing them.

Besides the convenience of the stroller, there is never any need to book a taxi with a child seat (at either end of the journey). Any taxi will do.