Should I add perlite and pine bark fines to Pro-Mix HP to use in a self-watering container or is it suitable to use as is?

Pro mix HP is high porosity used for rooting or establishing a young or a suffering tree. If you are setting up a self watering container, use a medium that has a good bit of compost in it.

If you want to use pro mix HP do. It add any bark or perlite since the mix is already formulated to be "airy". Mix some good compost.

I don't recommend using ProMix for SWP. Remember you will need somethings that can wick water up. Use pure mushroom compost. It's heavy, but works like magic.

Well that's too bad.  I thought I read somewhere that Raybo used Pro-Mix BX in 3-2-1 (the difference from BX and HP being the perlite content).

I experimented with plain, all-purpose Pro-Mix this year in 10g SIPs.  I added perlite and vermiculite to help insure that the pots never get water-logged in rain (I don't bag the pots).  The Pro-Mix seems to wick water just fine. 

The basic ingredient is finely ground sphagnum moss, which wicks really well,  right? 

Pro-mix is just fine.  I've been using it for years for SIPs.  As for adding pine bark fines, I don't think it's needed, but a handful would be ok.

Oh good, I'm relieved.  Now I won't have to drag that heavy 3.8 cu.ft. bale back into the car!