>>1767526well tubus is the best but that rack design seems not bad. I'm surprised it sways a lot.
The upper struts normally don't matter a lot, and p-clamps should be fine.
Are they the rubber/metal p-clamps like on the left though? The vinyl coated metal p-clamps like on the right have less mush. Switching to them might help.
And there's 531 and 531. If it doesn't have seatstay bosses for the upper arms then those dropout bosses will be designed for fenders not a rack, but still. It should be all good.
