Regarding my thread on a cold horse trailer... what insulation is best?

I looked on lowes.com and found this:

http://www.lowes.com/lowes/lkn?action=productDetail&productId=168290-210-LW1490LOW&lpage=none

and this: http://www.lowes.com/lowes/lkn?action=frameSet&url=www.dow.com/styrofoam/lowes/products/supertuffr.htm

 which seems like what I should probably use.  R-value of "only" 6.5, though.

Can I use any of this stuff without covering it with panels?  Breathing fiberglass ain't cool...

How do I hold any of this stuff up to the wall?

Finally, mold resistance is CRITICAL.  I hate walking into folks' horse trailers that smell like mold.  Living in the humid south, gotta have insulation that will not hold mold or foster its growth.

Thanks,

Mike