I wish to put floats on a Hanger 9 Ultra Stick .40. Can anyone recommend ready-made floats that they are sure will work?

With the Ultra Stick you have a light wing loading, huge control surfaces, and flaps. Even doggy old GeeBee floats will work.
However, if it were me, i would use a nice light set of foam floats about 36" long ( you could get by with 32s but the prop might be in front of the floats) There are several foam float sources listed on my website (below) and one I mean to add to the website is www.geocities.com/planefunfloats.
I flew a Jerry's Little Boy (Similar to the UltraStick) for three years on BJ foam floats, and it was completely successful. BJs are gone now, but the PlaneFun floats are very similar.

Hi Jim, I recently bought a set of 40 szie & 60 size floats from Planefun[Ralph Smith}, they are beautifully done. Hopefully I can get the 40's attached to an LT-40 ARF before the summer is over. Haven't decided where to put the 60's yet. Also, a great big "THANK YOU" to you for all your help and advice to us who are new to float flying. You have made the transition from wheels to floats a lot easier.

>>Also, a great big "THANK YOU" to you for all your help and advice to us who are new to float flying. <<

~BLUSH~
You just made it all worthwhile, pal.

I too recently purchased a set of 60 size floats from Ralph Smith. For under $90.00 they are beautifully finished, and ready for your final color scheme........

Now I'm blushing. Hope you guys have as much fun as I do. Float flying is truely addictive................Seaplane (Ralph Smith)