This is a pic of a mod of seen various places, usually on 179/180 models. I was considering doing this to my own 180, even bought cedar for the drawer body and aspen for the front and planed it down. Then I decided to do some checking before I started making sawdust. With the furnace running, I took some temperature readings of the un-modded space under the bed.

Here's the furnace temperature right at the warning label:

On the floor in front of the running furnace:

Directly above the furnace:

Probably best not to modify the area in and around the furnace. This mod is now off the table for me.

I designed a heat deflector that worked well in my 180, no drawer though. You could probably combine the two ideas.

http://www.rpod-owners.com/forum_posts.asp?TID=9066&title=3rd-180-mod-furnace-heat-deflector - Here's the link to the OP and a video.  Their's even a template to make it in the link, so far I know of 4 others that did it and they seem happy with the results.

(now i need one of those fancy thermometer things!)

Rgds John