Processing a seperate entity transactions without going multi org

I would be grateful to hear from anyone (especially another Council) who has set up Oracle Financials 11.5.10 to process a seperate entities transactions (in this case a charitable trust) on their behalf without going multi org. We realise that due to the legal status of the entity that we have to segregate transactions, customers, suppliers, banks etc. but the preferred option is to do this using a seperate company code in GL and seperate suppliers, customers, banks and invoice types etc. with segregation by responsibility and security rules rather than moving to multi org. If anyone has experience of evaluating