Floor Brace question...

[TimE]

On the front floor brace on the drivers' side under the pan, what is the purpose of the hole on the bottom and the one on the rear? I assume it is for drainage of moisture accumulation but what would happen, long term, if I were to weld these up and completely seal the brace to the floor pan?

The reason I ask is after removing the floor in my truck there was quite a bit of sand and debris inside of the brace that helped to retain moisture. Once the truck is reassembled, it will be used as a truck(i.e. dirt roads, rain, etc.) plus I live in a humid part of the country not too far from the coast. I don't want to weld the holes closed and seal it just to create another moisture trap for hidden rust to occur but on the flip side I don't want to have a brace that will retain crap to cause it to rust either.

Could the brace be modified in some form so that it could be cleaned out rather easily?

I plan to tackle this issue this weekend, in one form or another, so does anyone have any thoughts or experiences with this? I am completely open to suggestions/ideas as to what would be the best route to take.