I think you're worrying too much over something that hasn't happened yet.

Now, consider this scenario: You set up spoilers and just as you set the cub down on the runway (A critical point during the landing) you need to take your concentration away from flying for a split second to flip the spoiler switch - and in that split second, she noses over or ground loops because you were flipping switches instead of flying.

Don't expect your cub to act like the simulator. I have never seen a real cub roll out too long on landing.

Sims are nice, but they are not exactly like the real thing.

Just fly it. If it lands too hot, you probably need to move the CG back to slow it down, not add spoilers.