Creating Oracle User On Development Instance

I have been asked to improve the speed of our extract feeds to another team. It was using an excel file as csv created with C# reading the csv into a global temporary table and a procedure to insert rows from global table to main table one at a time.

Around 1 million rows That was taking around 25 min. After trying sqlldr and an intermediate table I managed to reduce timing to 15 sec with sqlldr and Direct Path Load. I tried all that in one of our own DEV databases. Now we want to try the approach in one of DEV databases belong to downstream group (the one we feed data). They are rather reluctant to give me access to their DEV database! I have asked them to create a new login and grant object creation (DDL) to this user.They keep saying that they are prepared to give me a role but NOT schema owner. What is the best way of enabling me to create tables somewhere and test loading times with sqlldr.

I need to do full DDL (table/proc creation) and DML on a certain schema. So my question: What is the best way of doing so.. Do I need a schema created for user to do this workI they already have a general purpose schema, can they create a role to have full DDL: rights in that schema?