Below is a picture of a deck that is similar in size/layout to the deck of our house:

The only way that would be relatively cheap (just putting up walls and adding another entrance in the existing footprint of the house) is if it already has a second bathroom, you want to end up with two one-bedroom units and the layout works to divide it like that.

I'm thinking of incorporating the layout design where it can easily be converted into multifamily. 

If I tie up all my capital in real estate, and I find myself needing $120K in tuition in just one year (2028 will have 2 overlapping, potentially 3 if private high school), then I may be regretting pursuing real estate.Am I thinking about this the right way? 

Good intuition @Leslie Thompson looking into this 9 years ago, i wonder if you ever "pulled the trigger" back then.

I really like the simplicity and layout of REI Automator.

I can't use any of there lumber layouts for this market, but I like laying out lumber and beams on homes that aren't typically built around here.

In reality I think quickbooks is more designed for professional accountants and large companies but a lot of consumers have stumbled upon it and Intuit is like "well if they're going to pay for it we're not going to tell them it's way more cumbersome and expensive than they actually need and drive them somewhere else".

You can choose the layouts and finishes of new homes to match your preferences and needs.

I thought a good place to start is to ask the question on what is the most cost efficient building layout?