I'm at work so can't give you exact measurements, but on the ones I bought, the area around the spigot has no insulation and was very thin, maybe 3/8". I emailed BargainFittings and he suggested that their valve bulkhead assembly for a SS keg should work since the cooler wall was so thin in that area.
As for the rest of the cooler it was fairly thick, so you'd probably need the cooler bulkhead assembly.
My suggestion would be to go down to WalMart or your local bigbox store (HD or Lowes) and checkout their 10 gal coolers. The design may have changed since I bought mine and this way you could see for yourself what the thickness is and whether it's uniform in areas you're likely to need thru-wall bulkhead fittings.
Good luck.