There can be more compliance work and potentially higher costs compared to just a Self-Directed IRA. 6) If you decide to rollover to a Self-Directed IRA first (your pre-tax money) you can always rollover that money into a Solo 401k when you eventually qualify.

I'm opening my second home and find them extremely rewarding but think I may stop at these two because I am extremely involved in them and am spreading myself too thin I think. 

I realized that the best way to compare and contrast these properties is to calculate the ROI of each.

Generally waiting at least 3 months will allow you to use the new appraised value compared to the purchase price so if you've done renovations that will help with your LTV for either a refinance where you change loan programs or rates (a rate and term refinance) or a cash out refinance that will give you access to more potential cash for your next project.More info on DSCR loans: DSCR loans won't use your income to underwrite the loan.

More risk = more reward.  

@Chris KittleIf you are unsure of costs, I would download some Offering Memorandums in your market and compare costs.

With this set up, we were able to get a DSCR loan through Kiavi with only a few extra steps compared to an LLC.  

I compared a 2.5% and 5% property appreciation rate at 5-, 10-, 15- and 20-year intervals.

Also, regarding the 15% you pay to Airbnb replaces the commission your guests used to have to pay to Airbnb so you should be able to charge it through your guests through your pricing.And, yes, operating short-term rentals in Mexico, while cheap compared to developed countries, is somewhat more expensive than in Colombia, Ecuador and the Dominican Republic because Mexico is more developed.

Quote from @Thomas Schmidt: You could hold off on paying until he gives a detailed breakdown of costs and compare it with local rates.