Good idea or bad idea?

[tam91]

I just started my first tomato seeds in the 20 row seed starting trays.

Now, I've seen that they are supposedly unsuitable for use on heating mats, because the small amount of mix in the rows would dry out too quickly. So here is my idea:

Again, I'm sticking them on the good 'ol Directv box. I've set the seed starting trays inside a solid tray, and covered it with plastic wrap. The seed starting trays are shallow, so there is a big gap between the bottom of the seed starting tray and the base of the solid tray.

What I thought seemed a good idea was to put some water in the bottom of the tray (not actually touching the seed starting tray). My theory is that the water will get warm and give off some heat. Plus, the water in the bottom should hopefully condense on the plastic, and generally make a warm moist environment so that the mix won't dry out.

Any reason this is a bad idea?

(yes, I know, don't give the directv box a bath)