Currently looking to get advice on a $50-60k private money bridge loan for my parents. 

Scenario: first mortgage $450k, property value $1.5MM - LTV 35%. Location - Santa Barbara county, CA. - current mortgage payment $4500

My retired parents are preparing to sell their house and rent for 1-3yrs while looking for a few smaller properties to buy. They are on a fixed income and will not qualify for traditional lending (as far as I know). They need around $50K bridge loan to facilitate a move into a rental/living expenses while we renovate their current home and then sell (4-6 month plan).  Credit score 670 - 1 random late payment to PayPal during Oct 2021, aside from that, they have little debt 1-3 credit cards carry a balance - utilization at 50%.  

Value of property as is - $1.5MM based on very recent comps in the immediate vicinity.  Value after renovation will likely reach $2-2.2MM based on very recent comps in the neighborhood.

I am not sure what their options are but seems like there should be some opportunity for an investor to earn 10-15% return on a short term loan. Does 10-20% seem too high? low? for the risk involved 

Renovations will be paid for by an outside investor and profits above the pre-renovation price will be split amongst the stakeholders in the project (i.e. parents, investors and project managers).

any advice or insight is appreciated