I've just rolled over an old 401k to an SDIRA and was wondering if funding direct mail marketing campaigns with SDIRA funds is allowed?

If you dont have a retirement from a big company that pays for medical and other things that us self employed have to pay for.. 

Lenders like income streams that have two years of history; if you're a W2 employee, you need two years of employment in the same field, and if you're self-employed, you need a business that demonstrates the same level of income for two years.If you buy some property for cashflow, a lender probably won't count the income until you've owned the property for two years.

It's a good thing I gave my self a large margin of error when purchasing this property.

If you need a loan that won't take into account your income there are two that come to mind, Non-QM DSCR and Bank statement loans.A Bank statement loan is used primarily for a self-employed and will require 12-24 months of business or personal bank statements.

I have heard that paying these taxes is a requirment to fund a solo 401k.When you get 1099 income, you will pay self-employment taxes (or FICA) with your tax return.

Here's the dilemma, my grandfather was a self-made millionaire, not a big-time millionaire, but probably a net worth of a 7-10million.

I originally wanted to self-manage (at least to start), but there are a lot of changes going on in my and my fiance's life, and I would rather hire a property management company now. 

I have been self directing 50% of my account for about 3 years and grew it over 500%.

Apartment buildings, single-family homes, duplex, triplex, fourplex, condos, RV and boat storage, Self-storage, etc...