Hi, I bought 2 ''self watering troughs'' from aldi last year, they call them self watering, because the drain holes are about 2" higher than the bottom of the trough, there's a plastic perforated tray, which sits above the drain holes, I don't know how this would work for perennials, but they're no use for annuals, as the roots don't go deep enough to reach the [now stagnant] water at the bottom of the trough. I think I would probably go for either a wicking system, or a drip supply if you could find some method of suspending the water container above the trough, Derek.

The watering system where you attach a spike to a soda bottle doesn't work, either.

As you've already got a sprinkler system, presumably on a timer? You could probably find connectors & small bore, flexible pipe that you could run up the walls using cable clips from well-known online retailers

I had self watering hanging basket one. The base that held the water was about an inch or and inch and a half deep. Rather than try to explain how it worked I found this link
https://homeguides.sfgate.com/wicking-material-selfwatering-planters-50337.html.
How long it would remain effective for would depend on the position of the planter - obviously it would last longer in the shade than in full sun but doubt if it would last a fortnight. However if you can find some large pieces of capillary matting you can cut it into long strips and hang one end in a bucket of water and make a giant version.

Thanks. I appreciate all the feedback!

Did you ever consider used Hydrogel Crystals? You can get some at the garden center. Mix it into to planting soil.

Water Jelly Crystals are an example of a water-absorbing polymer called a hydrogel. Think of these hydrogels as long chains of molecules (called polymers) that absorb incredible amounts of water, only to release the water to plant roots at a later time.

Thanks Bathgate. Sounds like that might be my solution. I also have a home in northern Michigan and am away a lot.