Wing covers, in my experience, are great at keeping the ice off but, early on a cold morning, result in very rapid ice formation on the wing as soon as the cover comes off. Not worth the hassle in my view - I've stopped using them. The TKS fluid works well, it's just a bit on the pricey side.
Does heating the fluid before using it make a big difference? Could keep it the warm footwell of the car on the way out to the airfield.