I do one flip at a time, I know my mental limits and I like to enjoy the process and not resent it out of obligation!

This, I would expect, would greatly limit the pool of potential buyer and does not make sense to me. 

In my limited experience portfolio lenders don't like properties worth under $50k and some of them even don't like properties worth under $100k.

I would purchase some land in a phased residential development, Anywhere.Don't limit yourself to Detroit or Michigan.

While some manufactured homes are attached to real estate by means of a permanent foundation, many more are not1 , and the collateral with which to secure the loan is limited to a title lien in the same way motorized vehicle loans are secured.

That goodwill will go a long way with your current tenants and limit their animosity toward you for raising rents.

One caution is a property that size will have a limited market since it won't be able to get residential financing.The quadraplexes look to me like a pure appreciation/speculation play - I wouldn't want to be highly leveraged on those. 

Does anyone have any recommendations on what would be the best first investment for a young investor like myself with limited capital?

Va loan limits

IF, FOR ANY REASON, SELLER (A) IS UNABLE TO MAKE THE TITLE INSURABLE OR CORRECT TITLE PROBLEMS OR (B) IS UNABLE TO OBTAIN TITLE INSURANCE FOR THE PROPERTY FROM A REPUTABLE TITLE INSURANCE COMPANY AT REGULAR RATES OR (C) DETERMINES IN ITS SOLE DISCRETION THAT IT IS UNABLE OR IT IS ECONOMICALLY NOT FEASIBLE TO CONVEY GOOD AND MARKETABLE TITLE TO THE PROPERTY INSURABLE BY A REPUTABLE TITLE INSURANCE COMPANY AT REGULAR RATES, AT THE CLOSING DATE, AND SUCH CLOSING DATE IS NOT EXTENDED OR OTHERWISE AMENDED IN THE SOLE AND ABSOLUTE DISCRETION OF SELLER AS SET FORTH ELSEWHERE IN THIS AGREEMENT, OR (D) DETERMINES, IN ITS SOLE DISCRETION TO DEEM THE AGREEMENT NULL AND VOID IF REQUIRED BY APPLICABLE LAW, AND/OR REQUIRED BY ANY EXISTING CONTRACT OR AGREEMENT BINDING UPON SELLER AND/OR THE PROPERTY, INCLUDING, WITHOUT LIMITATION, ANY AGREEMENTS WITH THE PRIOR OWNER OF THE PROPERTY, ANY MORTGAGE INSURER OR ANY MORTGAGE BROKER, THEN SELLER MAY CANCEL THE TRANSACTION CONTEMPLATED BY THIS AGREEMENT BY WRITTEN NOTICE TO THE OTHER PARTY AND THE ESCROW/CLOSING AGENT.