Accounting w/Excel - how to track Principal payment (not Schedule E expense)

[Jeremy T.]

So I tried QuickBooks and Buildium, both great and snazzy but ultimately using Excel is just faster and with Office 365 I literally create a clear audit trail (my job has me working with auditors everyday...) by inputting all transactions and including a hyperlink to where the bill/receipt/pdf, etc. is located on OneDrive. etc. etc. I'll post my system later once I answer this question and make sure it's all pretty close to following the right rules,...  but here goes - 

So my Excel spreadsheet tracks all business activities according to where it falls on IRS Schedule E - that is rents received or one of the items in the expense category. Problem is, I don't know where to put "principal" because while I want my spreadsheet to pop out what's needed for my CPA I also want to see the end of the day cash in and cash out net. Currently, I am categorizing it as an Asset (choices: Asset, Expense, Income) and leave it blank in my column that has the Schedule E choices. 

Is there a better way?