You already figured it out. Pain a contrasting color and some type of directional pattern. What ever you do it needs to be noticably different top to bottom. Be careful how much paint you use as paint will add weight quickly.

How far out are you letting you plane get??? That is a small plane and you want to be crarefull getting it out where you can't see it well, even with a good contrast in color.

Have fun and be safe.