NOTE: YOU WILL LOSE ~3 SECONDS OF FOOTAGE WHILE THE RECORDING STOPS AND RESTARTS
Now we have that out the way:
Put RecordingSplitter.dll into: 32bit: Program Files (x86)/OBS/plugins 64bit: Program Files/OBS/plugins
Recording length is set in: Plugins/Recording Splitter/Configure By default, it is set to 30 mins. Splitting of 10 seconds upto 1 day (well, 23hrs, 59 mins, 59 secs) are possible.