If you want credits you can always edit the save file. Unzip it with 7zip or Winrar to get at the actual XML file similar to rebirth. Then do pretty much what was done in rebirth. Search for your credit amount which is in a few places in the file and put in however much you want. You can then use 7zip or Winrar to use gzip and recreate the compressed save.
Personally I can't wait until they slow down a bit on the hotfixes and we see options like infinite boost. If I recall that's the primary use I had for the Rebirth trainer. Most of everything else is a quick save file edit generally speaking.
yup, credits was an easy hack/cheat from the save game file.