Hi Julia, Here is an all in one unit, Tail, Brake, Turn and Backup, you would only need a pair to do everything. Check out their video, the turn signals strobe! Currently $30 minus 25% off. You could mount these way out to the edges of your rig to give more clearance for your kayak .
These are the ones I got that dont have a backup light and required two pairs, $21 less 10% coupon per pair (I wired in two LED spotlights separately angled to the rear and sides for those late night backups in the woods...
NOTE: When drilling mounting holes in the plexiglass cover use a sharp bit, don't apply too much pressure, and drill the holes slightly oversized of the screws. Otherwise you might get plexiglass cracking at the holes.