I put my vanguard 15 (almost 200 lbs) upside down on top of the beams of my nacra 6.0 for a 3 hour drive.
I just put thick cushions in the front and back to elevate it above any hardware on the beams.
That being said, i'm not sure how far of a distance is between the beams on a 5.2 and if the El Toro will reach both.