It's debt you'd still have to pay back, but at least you will not touch one of those two amazing interest rates. 

Would it be worth exploring the possibility of partnering with an investor somehow to help with funding?

Should I price the land 2 times above market value and offer a low interest rateORPrice the land at current market and use a very high rate?

They already lost some major players due to the state capping rates https://www.foxbusiness.com/lifestyle/california-insurance-c... will all insurance companies stop coverage, raise rates or reduce what they cover?

The main reason I decided to sell rather than hold was the rising interest rates.

One other advantage is that many of the builders that I have worked with are able to incentivise the sale with interest rate buydowns that make the deal work.Best of luck moving forward. 

If have investment property, we are looking for relatively updated units (we are ok doing some work ourselves), class C+/B tenants, with rents either close to market rate or that can be increased.

Any other expenses are using up funds that would otherwise be sitting in your checking account to make a mortgage payment with.

If he must attempt to get the low interest rates of 2021 on this deal, I suggest that he instead look for assumable loans.

Also, how much time do you want to spend doing real estate vs. your main job or extra work in order to fund it.