Yes there is a way to install a single box installation. But first, As a disclaimer, the resources involved in collecting data often make it a poor choice to colocate with a search head or indexer. There are no sizing guidelines for a single box installation and if call support for any issues the first thing you will be asked to do is to move data collection to another machine. Now that that is over on to the how to do it.
The Splunk App for NetApp Data ONTAP utilizes the Hydra data collection framwork (that's that SA-Hydra app that ships with it). It follows a fairly ordinary client server paradigm if you consider the scheduler node (typically run at the search head) the client and the data collection nodes as servers with data collection services. So to install on a single box you need simply make that box both the client and the server. This amounts to a normal install except that when you come to the add data collection nodes step you simply add the splunk instance you are configuring the scheduler on as its own data collection node. Thus your data collection node's management URI would be along the lines of https://localhost:8089.
Note there is also a security concern with this methodology as this machine will have its own service account stored for logins. With that and the resourcing concern I would really only do this for as simple a POC as possible and never in production.
