There was some stuff called (I think) No Sand Primer.
It costs a LOT but will save labor.
If it were me and just worried about the looks, I'd pressure wash it and lightly repaint with as cheap a paint as possible. Most bottom paint doesn't do well on the trailer anyway.
http://www.yachtpaint.com/Images/15_20616.pdf
And I think this price is a quart.
http://www.westmarine.com/1/1/27515-...-interlux.html