Power for small summer use cabin

First I will assume since you don't mention it that you do not have grid power. You also don't mention refrigeration, do you use ice chests? What you mention is not much at all. How many persons are you planning on accommodating for charging cell phones, etc. I have a small solar panel which came with a portable lithium battery pack that allows for 3-4 charges for a cell phone and that can charge the pack or phone directly. There are a few manufactures of things like that which are used by backpackers. It might be easier for you to get one of those for each person and make them responsible for charging their own phones. Your existing batteries make me nervous if you are counting on them once you arrive at your destination. UPS batteries usually don't last as long as you have had them and are not always suitable for charge/discharge on a regular basis.

Also, if this is purely recreational and sporadic use, I have both Coleman battery lanterns as well as oil lanterns even though I have grid power. There is also a category of battery solar "generator" that comes pre-configured for campers and includes solar panel, charge controller, battery, etc all in an easy to transport package which might be of interest to you.

However, if you want to learn solar and maintain batteries and make a hobby out of this, you could certainly design a small system which would not necessarily be small in price, relative to the use you are communicating.

7 years is a long time for sealed batteries, so don't get too attached to them, when you start using them they may flake out on you quickly.

7 Year Old Batteries = BOAT ANCHORS

Two 7 year old batteries is enough to drown a Lawyer and a good boat anchor.

That's right, we are off the grid. We do have propane refrigeration. We do have battery powered lanterns, kerosene lanterns, etc..but the convenience of flipping on a light switch is appealing. Not to mention easier and safer for the kids (off the grid and no fire department to assist). I know that the system I'm talking about is probably overkill, I'm good with that. The batteries (aka boat anchors) I have use cost me nothing and may be worthless, hopefully not but we will see.
Let's just say the batteries were new. Any suggestions on solar panel or charge controller given the low use and light loads? Anything else that I might consider?

I will keep that in mind if the wife annoys me too much

Well if she is at the store like Wally World with you and ask where the batteries are; you know it is over.

I am just learning now too and don't have any practical experience. If I were in your position I would probably want to salvage the batteries too. I suggest you test them, because if they are not suitable for using as cycled power you will want to match your charging equipment to the batteries you end up with. I would get a three-stage charger that you could use with your generator first. Since you don't need AC power yet, hook up some loads to your batteries after they are charged. Get some leds and phone chargers. Calculate the load and run the loads until you get the battery down to about 80% (ie only use 20% of their rated capacity). Look up the voltage for your batteries to verify that you drained the battery to ~ 80%. Then charge again with your generator and do it a few times. If the batteries seem to perform then you can invest in a charge controller and solar panel to match the size of those batteries.

The charger that you get will continue to be useful because it is a good idea to have generator backup for any solar system.