What are some reasonable options for an 8 hour transit from EZE (international arrival on an overnight flight) to AEP (domestic connection)?

1) Take a taxi from EZE-AEP and spend 4-5 hours at AEP. Are there any lounges with showers at AEP?

2) Hire a car with driver and head into BA centro and have a leisurely lunch and do some shopping/sightseeing and then head to AEP? Is it safe to leave your luggage in the back of a car of a hired car with driver?

3) I don't know if this is possible, but if there are any hotels in BA centro that offers a day rate - check in at the hotel, take a shower, leave your luggage at the hotel and spend a few hours in BA before heading out to AEP?

Also, are there any shower facilities at EZE for arriving international passengers (e.g. Arrivals Lounge at LHR, FRA and HKG)?