I don't think you understand the commissioning process. Why would you go to an SMC and not do ROTC if you are going to do ROTC at a civilian college?
It doesn't make sense.additionally if you do ROTC and graduate, you will commission as an officer and there would be no need to do OCS/OTS.
The biggest difference between an SMC and a traditional ROTC program is at an SMC you can't be in ROTC without being in the Corps. You can be in the Corps without being in ROTC, but again why would you do the Corps and not ROTC with the end goal of doing OCS?
An SMC lifestyle is much different than a traditional college ROTC program. It is more like an academy lifestyle. You will live in ROTC only dorms. You will have a much more stringent life.
OCS is for those that graduate from college and did not graduate from ROTC. OCS is a completely different program, including the application process. They have their own boards at specific times of the year. OCS can be seen as the stop gap. It is also a path for enlisted to apply to be an officer. What I mean by stop gap is that if there are too many being commissioned for that year group via USNA or NROTC or even a specific career field, they can cancel the board or take more in if there too few. For the AF they cancelled two of the last four OCS boards because the AF had enough in the pipeline while they were also going through downsizing. If the Navy in four years finds themselves in the position of downsizing like the AF, chances are they too will cancel OCS boards.
What would you do at that point? If you say enlist.....rethink that because once enlisted your Commander would have to agree to release you. It could take years before they agree to release you. That now means had you gone to college and done ROTC by the time you get through OCS your classmates would be an 02 maybe an 03. For the next twenty years oif you make it a career they will be making more money than you, and when you retire it might mean you retire as an O4 while they retired as an 05. That is a lot of money you are giving up for the rest of your life because you decided to do OCS and not NROTC.