An alternative to clear fins is to use flat black and make the butt end of the crayon completely above the fin can area. Especially with brighter colors on the main body, the fins tend to be demphasized. One could take this a step further and play with camoflage patterns - further demphasizing the outline of the fin area.
I'm doing a crayon rocket right now (a small BT-55 LPR version, not the typical big version) and plan to use the above approach to make the fins less prominent.