Bike with Paul's Flatbed Porteur rack ..
Wrapping a toe-strap around downtube and wheel-rim keeps my Ft wheel straight.. when I stop.
Made a side release buckle/strap that is held by bolt in the upper bottle boss* .. so its always there..
* frame such that there are 2 bottles able to go, on top of down tube...
often with a heavy pannier only on one side of the front rack.
thats your problem, you can get away with an unbalanced rear load, less so on the front.
2 panniers up there so the wheel wont drift off line so easily..