What is the best way to stap my hobie to the trailer?
I have a very agressive approach. I've got a rope tied around each pylon that I use for tying down the boat on the beach (to doggie stakes) but when on the trailer if I'm going to drive it, I'll pull those tight to the center crossbar of teh trailer (right above the axle). Then I also have 31" black rubber bungee cords that go from around each pylon down to the trailer crossbars underneath them. In the back that means above the license plate and in front it's sort of at the back of the Y in the trailer. 
I recommend buying those straps with a ratchet. You can find them at most hardware stores, and get four, one for each post. I haven't seen Jaime's rig, but I'm leery of bungy cords since they can get bouncy, and I'm not really good at tying tight with rope. Also, make sure you tie the boat down with the straps either all inside or all outside the posts on the hulls so the boat won't roll off.
Use a "trucker's hitch." If you tie it with a figure-eight-with-a-beight rather than an overhand-with-a-beight it's easy to take out and you can get it as tight as with a racheting tie-down; plus every racheting tie-down I've ever bought has broken on me after a short period of time. 'Course I always have bought the "$10 for 4" ones... 
Agree with rachet-typs straps. I recently bought a pack with two long rachets and two shorter non rachets. I put one long fore and aft from trailor, over hulls to opposite side of trailer. I use the shorter ones to hold each hull down to the trailor. Takes 5 min or less and my H16 is glued to the trailor -rock solid. Travel regularly 2 hrs back-forth without any loosening issues. Good luck
yeah, if you do it right you can tie normal rope just as tight as one of those things. bungee chords on the other hand... well i would be nervous with them holding my boat down. Maybe the ones you are using are alot more hardcore than normal, but the ones I'm imagining would be kinda insignificant compared to the boat.