Hmmm little different scenario there. I have been told that once you use a tank for VO you should never put Diesel in it again. I dont know why.
Once again I suggest you contact Lesk WVO to get an answer to that question.

My thoughts are pick a system and go with it. Any time I have watched someone try to embrace multiple paths to the same objective it ended up costing them in the long term.

I guess my question is if you are going to run Bio Diesel why bother with the VO at all it will essentially double your initial setup cost, may lead to problems, and is an unnecessary complication.

Just convert all VO into BD and don't worry about it if you find some one giving away #2 just smile and fill up your tank. Or mod your truck to run VO and dont worry about that occasional #2 bargain cause your never gonna find #2 as cheap as WVO.