Yes, if you know the lenders who do not care about seasoning, no if you do not or get the money and season it so the deposit can't be seen.Now, that is a nightmare scenario and let me tell you why. 

That's more like a typical security deposit to rent an apartment, lol. 

The seller’s most recent counter-offer was 90k for 30-40 day closing with a 10k non-refundable earnest money deposit.

I'm absolutely not interested in leasing fast at all and I'm extremely picky about tenants and I do things like require a large security deposit (even for section 8 renters, I have three of them and love them), don't supply appliances, take my time doing background checks and arranging multiple calls/meetings with potential tenants. 

Don't be surprised if the insurance company has the family provide the security deposit.

Screening tenants well and then a security deposit or credit card hold process in place will limit liability.

Best practices for security deposit deductions (damages)?

You need lease and deposit check at closing so the property has to be move in ready not a rehab.

For example, I often see Buyers purchase property thinking there is a $1,000 deposit but then the tenant claims it was $2,000 because they paid the last month's rent.

Financing-  build a relationship with a regional banker, don’t shop for interest rates, start small and build history and loyalty they are your team, Cross collateralize, deposit CD/MM or custodial account with bank for loan, give them monthly updates, nail your deal analysis, do stress tests on your deal analysis-cost/interest rate/deal length/ sale price etc. 12.