HIt up a local shipping business or maybe you know someone who works in an office or something of that sort that could maybe get some for you? Could try USPS? They give free shipping supplies, well boxes I know they do for sure.
Well, i found some packing peanuts, and it looks like about 1.5 cubes. Too big for sealed, too small for ported. I think i might get some of that "great stuff" spray foam and fill up some of the odd ends to get down below 1 ft^3
Have never used a Type-RRRRR but most subs will play better in a large sealed enclosure. I would try playing it for a day or 2. If you don't like the sound than I would use the expanding foam. Its easier to put in than take out.
The fact that the volume is greater than you expected will give you more linear response and better impulse characteristics. Although the sound will bee "more musical" you may notice it's less "punchy". Try adding some bricks of hard foam or even pieces of wood to find your perfect volume (make sure they are secured inside and not rattle). After that you can replace them with the same amount of expanding foam.
Do not put too much - or you'll get ugly boom-boom sound. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif