It seems like you would have the funds required to take the HELOC or just from investments.

Be aware that the lead paint laws require you to delead rental units within 90 days of closing in order to not be liabe for past tenants.

The ones that require leverage are not the greatest though (just like when leverage was cheap they were great investments)

My bank requires $1,500 in each checking account at all times. 

Required down payment is typically 20-25% depending on FICO, property type and level of experience. 

Our ski in/ski out STR in Colorado only went online late Dec. 2023 so my data is very limited.

Doing research online, it seems the price of an ADU might be around 350k8.

Another reason why engaging an architect early is helpful is to ensure the layouts are permitted from the perspective of code requirements.

Of course, with all things, the answers to all these matters will depend on the circumstances.California tends to have more laws on the books and requirements and restrictions that it can be a good idea to form a CA LLC for out of state property so that you as a CA resident are covered, and to try to have your contracts fall under the purview of CA courts.

As such, there are strict requirements that Hawaii State Law Quiet Hours must be observed outside the home past 9:30 PM (feel free to go snuggle up with some popcorn in the 16-seater movie room!).