what i thought of is more like the Kamae stances in yoshinkan, something like that .... the tai sabaki idea is a good one
One suggestion I remember which was told to me when I asked my instructor a similar question:
1) Stand in Kamae (when feet are spaced properly, you're ready for seiza without moving feet).
2) Begin seiza but do the movement much slower (say 1/4 speed) than normal and stop (don't continue seiza) when your first knee (ever so lightly) touches the ground.
3) At the same speed you went down, come back up to kamae.
4) repeat 5-10 times then switch sides.
Control of posture and balance (roughly equal pressure in both feet at all times) should always be in mind and your quads get quite a work out.