In BE no problem, but indeed stay out of controlled airspace, which already precludes KOK-COA at any altitude.
In NL remain below 1200' AMSL - sounds unattractive but in such flat country it is not impossible. I don't really know about your chances of being allowed in Controlled Airspace in NL with no transponder, but I feel they are slim at best.
Also don't forget you'll need to pass immigration (aka "customs") , I do not think this is available at Teuge so you'd need to land on the way. Options include LFAC Calais, EBKT Kortrijk, EHMZ Midden-Zeeland.