45 minute connection at AEP
 

An illegal connection I know but...

The 1st flight from Salta (SLA) to AEP on a Sunday (on LAN Argentina/4M) arrives 45 minutes before a AR flight to Trelew (REL). The next flight isn't for another 5 hours. If we were to buy a 4M ticket for the flight from SLA, and a separate AR ticket for REL on the later flight and got to AEP on time, would AR gate staff let us go on the earlier flight - assuming seats are available? We'd pack light and have hand carry bags if this is possible.

I suggest that you take the 5 hour connection despite little to do at AEP.
The seating does allow one to take a nap across a group of seats. The only saving grace for your strategy is that you are coming in on LAN and out on AR which has a tendency for irregular operations.

AR probably will not be flexible unless they have seats and you pay a change fee. Whether that can be done in the secure area is a question I cannot answer. I recall that last year the change fee was something in the $25US range per person.

You also have the added issue of carry-on restrictions (LAN's allowances aren't always so generous) and you may end up having to check your bag.

Looks like unless the 4M flight arrives quite early and the AR flight is delayed, the connection just isn't going to happen. I see that all fares except the ejecutiva (full biz) fare have a USD 25 change fee, and I'd bet they wouldn't allow free standby so one has to go landside.

Thinking of taking the AR flight that goes SLA-JUJ-AEP for sightseeing en route but there's the worry that flight is delayed (flown AR some 10 times in the past 18 years and would say at least 30% were delayed, one of 21 hrs).

Yeah, I know AEP is boring but it's better than the one-storey terminal that was used in the early '90s. Maybe take a taxi/bus somewhere and get something to eat. We won't arrive into REL until late.

Alternative is to fly 4M into AEP the night before and then fly to REL either early AM or mid afternoon the next day.

Just hop over the road to the "promenade" and have a stroll if it's a nice day.