I would use a 5 gallon carboy to minimize head space. I think the extremely slow action of the Brettanomyces and bacteria will have a minimal kraeusen. You shoud be sure to have some food for these microorganisms to consume, residual unfermentables from primary fermentation. You might even consider adding some malto dextrine- say 4 to 8 ounces.
I would not introduce oxygen at this point, as pediococcus does best at low to no oxygen levels (i.e. less than atmospheric oxygen.) Pedio will be responsible for most of the souring of youur beer.
You might also consider not racking to secondary, or transferring some of the trub from the primary if you do. Brettanomyces have special nutritional needs (vitamins and amino acids), and can and will consume the autolyzed saccharomyces cells.
I have a p-Lambic on the primary cake for 16 months, and each time I pull a sample it tastes better and better! If after 3 months or so, you don't see a pellicle, you can add some bugs from your favorite gueuze dregs; also, I have found that Jolly Pumpkin has some active bugs, probably because their beers are much younger than commercial gueuzes.