I have a few packs of the Lowes “Harbor Breeze 4 -Pack 5 -Lumens Black Solar Integrated LED Path Light Kit ( 3500-K )” which is Item #2851250 and the one I'm looking at on the website is Model #QS73P-K5C-BK-4. (If this doesn't match your search terms I don't know what will.) And they all fell over! The included posts are cheap! (About as cheap as the kit) They have too thin posts, who's corners just crack if you look at them wrong. Or if you live in an area of high winds, or if you're not too careful with the lawnmower.

I went through several ill fated designs and landed on this one. It's not the same as the inexpensive anemic post you just threw away, but it looks damn good and works great. And those two things in probably that order are what's important here.

I printed it in PETG which should be fine up to 176f (80c) if random websites are to believed. If you believe other websites pavement can be between 30f to 50f hotter than the air, so know your needs and choose accordingly. Maybe do your own research but in a library or just yolo it.

I beefed up the corners where it would break so it's nice and thick. And because cylinders are strong and objectively really cool (and have less surface area) I made those slightly thinner in all the ways you might consider.

I kept the over length to 200mm like the original but it can easily go as big as you desire. You can probably stretch it in the slicer bigger without issue. Modify the SCAD or ask me if you want smaller.

It printed fine on my unmaintained Prusa MK4S. No supports but I doubt your slicer wants them. Despite it being tall and skinny it didn't fall over. I think the beefy end bits did us a favor there.

Keep your lights upright and keep your lights lit.