To be honest, there is no such thing as an easy 5. All of them have challenges, but there are some that are playable, but will provide challenge. I have always been partial to Holst, Vaughn Williams, or SOME Grainger works that are not easy, but playable. I have found that if you just take it slow and teach EVERY single little thing it can be done, but you have to leave no stone unturned.

I have had success with Molly on the Shore with weaker bands that did work hard. Holst in Eb is tough, but I feel is a little easier than Holst in F, but that is all debatable. I would avoid Suite Divertimento by Gilbert. You want MUSIC, not random sounds that are easy to follow.