Reinforcing a seatpost rack
I'm planning a few plastic card trips for next summer. Even with Visa, I need to take some stuff on the bike and, for this, bought a seatpost quick-release rack. I couldn't find anywhere what's the max weight limit it can master without breaking or bending the seatpost. Not willing to take any chance on this, I thought to add two alum plates (one each side of the rack) which would be attached to the rear wheel skewer axle.
I plan to have 15-20 pounds on the thing. First question is : is it worth the effort to add those side plates to the rack ? Second question if "yes" to the first, is the skewer axle able to hold the plates ?
Skewer is steel and seatpost aluminum 27.2 mm. Rack is Ascent Pannier seatpost rack as seen below. BTW, I didn't use a conventional rack because my road bike has carbon rear triangle without any eyelets and I knew I wouldn't have that much weight to put on the rack.