A lot of LEDs are just plain junk. I've thrown away my fair share.
The ones I'm currently using on our motorhome steps are sold by M4. I found them through the RVGeeks YouTube channel.
Here's how I've set them up.

I have one more to install on the outside of the coach, just above the electric steps. It should illuminate all three nicely.

If you still want to use the channel and add your own LED strips, here are the ones I've used on a previous project, which are waterproof:
https://amzn.to/2ygz4ni
I usually bury the cut end, and the soldered end, with glue from a hot glue gun. This waterproofs them very effectively.