I started my own very small LLC with myself and sister. I own 99% of the company. I won a government contract which requires 1 person to have a secret security clearance which I have had recently. Can I be the FSO, ITPSO, Senior Management Official, and key personnel? I would wear all of the hats.
There is nothing in the NISPOM that says the same person cannot hold the roles, but contact the DSS Field Office responsible for your company FCL. http://www.dss.mil/isp/overview.html
As Marko has already stated, nothing in the NISPOM states that you cannot perform all roles. In fact, many companies, especially those starting out, have to multitask the roles because it’s not economically feasible to hire people to fill all those positions.
It is very important to understand your full requirements and training of each role. Just be sure you take the time to do it right and don’t be afraid to ask for help.
Good luck to you and congrats!