When I made some changes to the property and put it back on the market about 15 months later for double what I paid, it was under contract in 48 hours.

I know for sure that in my area of Texas (well outside of major metro areas), we've seen the cost to build new homes almost double in price. 

Obviously this won't work for a  5 bed but if you are just getting 1-2 roomers  check the policy.

@Ewa Reza Are you asking where to stay when you go to Costa Rica, or are you asking if you were to buy your own AirBNB in Costa Rica, where would you buy it and should it be a 2 bed room or 3 bedroom?

In 2022 I purchased a 3-bed/2-bath condo outside San Diego for $535,000 with intentions to buy and hold.

The unit consists of two beds, one office and one bathroom.

I carried double the cost on Gas and Electricity to be safe. ==== Projected Income ====**Off Season**-$4,000/Month Rent Period: September - May (7 Months) Projected Income: $28,000**Summer 1**-$8,000/Week Rent Period: June (4 Weeks)Projected Income: $32,000**Summer 2**-$8,500/WeekRent Period: July-September (12 Weeks) Projected Income: $102,000**Optional** (Basement Apartment)-$2,000/Month -Rent Period: Year Round Projected Income: $24,000TOTAL PROJECTED INCOME: $186,000 ==== Operating Cost ====-Mortgage: $84,000 ($7,000/Month) -Utilities: $36,200Gas $6,000 ($500/Month) Electricity $6,000 ($500/Month) Internet $2,400 ($200/Month) Garbage $5,000 (Estimate) Pool $4,000 ($250/Week)Landscaping: $4,000 -Mowing: $2,400 ($150/Week)  -Clean Ups: $1,600 (Spring & Fall)-Weekly Turnovers: $8,800 ($550/Week)==== Legal Cost ====Summer Rental Fee: $20,100 (15% of $134K)Sandwich Rental Tax: $6,855 (15% of $45,700) NET PROFFIT: $38,845.00

Let’s say I invested in another investment which doubled every 7 years.

They can get time, but they’d all have to double or more their investment (if any of these assumptions are right).  

The note can't exist as a stock simultaneously because in the securities world it's a fraud known as double dipping.