Let's differentiate between SCAMPI "A" Appraisals and the process improvement work that needs to take place to be "performing at a level of maturity."
You can always skip an appraisal, so the short answer is "you could" go directly to a maturity level five SCAMPI A appraisal.
The longer answer lies in the realization that all of the work in the ML4 PA's (OPP and QPM) will STILL have to happen because CAR and OID (ML5 PAs) depend upon a statistical understanding of process performance that includes Process Performance Baselines and Process Performance Models.
There are examples of companies that have developed robust satistical process control processes, including PPBs and PPMs, and have used them to quantitatively manage projects, but have chosen to not conduct a ML4 SCAMPI Appraisal against those processes. Then they develop and implement processes for OID and CAR, and eventually conduct a ML5 SCAMPI "A" appraisal.
But I'm not sure why you would want to do this. It seems like a risky strategy to me - what if you conduct your ML5 appraisal and all of work you've done for OPP and QPM is inadequate? What if you misundestood the very specialized content of the HM process areas? What if your data set is statistically invalid?
If you're trying to do this to save money on the appraisal, I would argue that the cost of the SCAMPI A is insignificant compared to the effort you are putting towards achieving high maturity performance, and in the grand scheme of things it's not worth the extra risk.
An additional consideration lies in the concept of organizational learning. Your OU doesn't learn all at once, but learning takes place incrementaly. Why not achieve ML4, learn from the data, become experts at SPC for software, and then dive in ML5? Your chances of getting real value from the PA's is far greater if you take this incremental approach.