I'd rather pay a bit more in field fees to make up for your losses in BB's than be forced to use any BB (I don't know what PB entrance fees are but $15-20 sounds reasonable for something I'd pay). Hell I would even do field work and build days for free if you adopt a BYOBB policy for airsofters. One thing you'll notice with us (depends how you go about your business) is that we don't tend to have as many "electro toting agg muppets" and I feel there is a lot of camaraderie and people just looking to have a fun time compared to paintball. Make the "real" airsofters feel welcome and support their growth and you should be able to run a successful side business (because doing an airsoft only field is generally a losing game unless you do something cool and unique like "The Mall" in Reading, UK or Xtreme Tactics in Manitoba). Also please make sure you run a tight ship or your airsoft games can and will turn into a gong show, it's happened a few times before that I know of when experienced field marshals are busy and newer field marshals try to fill in their place (safety briefing takes too long, games not tailored to the people showing up or numbers showing up, etc.).
Also my guns are finicky as well. My pistol will only accept certain brands with certain tolerances or it will chop, jam, and feed like shit (as well as damage parts that although are cheap to replace still take time and is consistent with the damage since it's a result of the chopping/jamming).
Can't really go wrong with making BBBastard your field BB, HOWEVER there is a supply issue at the moment (from the release by Scarecrow (who I trust) it's through no fault of his own and although may sound like a conspiracy theory meddling from bigger players in the BB market) and if you stick to one brand you may be crippled if things happen again.
The other brand you should think about carrying are Green Devil (love these as well as the UK players that I know, plus they're Bio BB's and actually feed in PTW's (super finicky with ammo or it will chop BB's and force them out of the barrel like it's confetti)). Do your due diligence and look for more reports of their performance
. "The Bent Barrel Gun Doctor" is the business you'll probably want to talk to regarding carrying these.
Other brands that I like and think are OK (but may or may not be finicky) off the top of my head are: Excel, Guarder, Madbull, and Airsoft Elite. And a new brand that I've been approached to test and review called Calibre Six (so far results are awesome and IMO almost gives BBB a run for their money if they can put more money into R&D).