Hot water turns to steam, unless you bottle it in, when it turns to pressure. You better have somewhere for the steam to vent to. And it's far easier to let it vent to the surface and cool it sacrificially, than including the weight of a condenser and trapping all the heat in your craft - you certainly can't radiate it away axternally, you're surrounded by superhot plasma.

Don't worry if it freezes, so long as the piping can contain the freezing pressure. That's extra cold that has to be used up befor your water turns to steam.

But the idea of a large surface area is a bad one...

1) Doubling the surface area double the decelleration - the "g" loading. Existing capsules pull 3 g. your saucer has about 100x the base area to volume ratio of a compact capsule - leading to 100g re-entry loads.

If your capsule was strong enough to take this load (strong =heavy, BTW), THEN it would flutter gently to the groumnd and you could scrape out the contents and try again. :-(

2) wide flat shapes are intrinsically unstable. You DON'T want to flutter during reentry since this leads to violent shaking, irregular heating, and possible destructive forces requiring a strong and heavy airframe again, and more astronaut jam.