If you are "profitable" as a one-person company; make sure you are paying yourself a market-rate salary or are at least factoring in your time as a cost. If not, your SaaS acquistion metrics could be way off.
An employee thinks in terms of salary and hours of work invested.
An entrepreneur thinks in terms of investments and compounding returns over calendar time rather than hours worked. This makes sense because proper compounding returns will always outrun hours worked in the long run.
I've done it by doing an all in CAC calculation and then a non-labor calculation and then playing with weighted averages of the two and trying to guesstimate a split. Is there an accepted canonical formula for this?
Re: wearing different hats, you should still be able to come up with a % of time spend on actually doing marketing+sales and allocate accordingly.
I don't think there's one canonical formula. But here are David Skok's thoughts:
"To compute the cost to acquire a customer, CAC, you would take your entire cost of sales and marketing over a given period, including salaries and other headcount related expenses, and divide it by the number of customers that you acquired in that period. (In pure web businesses where the headcount doesn’t need to grow as customer acquisition scales, it is also very useful to look customer acquisition costs without the headcount costs.)"