Well then, I think this one would be too aggressive. This one is
Salix chaenomeloides and if I let it go, I estimate it would grow 30 ft. Every other year I chop it to 2-4 ft., after which it grows 6 ft in one season.
I am sure
Salix gracilistylis 'Melanostachys' is much more reserved for you. Another good one would be Rubykins. it is much taller (mine is 10ft), but more wispy, and not a strong grower as willows go, with very small and pretty pink/red catkins.
Also
Salix cinerea 'Variegata', looks like a wild pussywillow with variegated leaves, and
Salix shraderiana would do well. Shraderiana is the latest blooming willow species, but not as showy..
Okay, bad pics, but better than nothing...
Rubykins and schraderiana
cinerea 'Variegata'
variegation fades as the summer continues.