Does a very small via reduce the drawbacks of a non-filled via-in-pad?
Smaller via will reduce the effect, but not mitigate it. 0.3mm via can still wick a fair amount of solder from a 0603 pad.

Screaming Circuits have lots of articles about vias in pads. Have a read through them.

One option, which would not cost anything extra, is to tent the vias, as shown below:



My advice, though, try to quit your bad habit of using via-in-pad EVERYWHERE. I doubt your two-layer designs are so dense anyway and you won't make your life much more difficult by placing a via a millimeter away from the pad.

If the application justifies it (e.g. under a 0.5mm BGA), then you can also justify the cost of plugging the vias.

Have a look at my two-layer layout of a dual op-amp circuit. All passives are 0603 and I didn't need to use a via-in-pad.



EDIT

Here's a closeup of the actual PCB.