Lots of ways to skin a cat. One packet of lacto is fine. I do a starter for 5 gallons and worry that it wont be enough. Also, wyeast bugs arent the same cell count as sac yeast, much less. So if you are doing one batch on roselare and one on lacto/brett, just pitch the smack packs. It might be more than you need but I don't see it hurting anything. Mash temps is your call. Lacto likes short chain, brett will fo either. So maybe hit the middle?