Unfortunately some of these costs are fairly close to fixed whether you are renovating a $250,000 or $5000,000 house which makes it even more challenging to operate in the lower cost housing space.

Unit AppealAmenities and Upgrades: Although you have renovated the units, consider adding amenities like high-speed internet, in-unit laundry, or community spaces that can increase appeal.Feedback Collection: Gather feedback from current and past tenants about what they liked and disliked about living in your units.

I have found several with two entrances / split levels and a common laundry space such that I could rent 2-3 BR to another family or 2-3 professionals and earn $1500-2000/mo on a $200-250k purchase while living cheaply in the other 1000 SF of the house and having limited forced interaction with the roommates/tenants. 

You need more space and more safety than say, a regular single male would.

Explain your worries about potential damage to the new porch and noise disturbance, especially if it's causing vibrations that could affect the structure or annoy neighbors.Consider Amendments: If your lease agreement doesn't currently address items like punching bags specifically, consider adding an amendment that outlines rules for using outdoor spaces to prevent future misunderstandings.Document Agreements: Whatever agreement you come to with your tenants, document it in writing to ensure clarity and as a reference in case issues arise later.If you need any further assistance or would like to discuss please feel free to DM me!

Our detached garage is about 325 square feet now and half of that space was legally converted to a recreation room with a bathroom in the 80s.

You can get into a 3-4 family properties (3 to 4 family is preferred since it is tough to find a duplex now that cash flows once you move onto your next househack) with as little as 3.5% down (FHA loan, you can only have one of these outstanding at any given time) vs. 5% conventional loan (you can have up to 10 of these on your credit report before you essentially run out of space) and create an investment property with little money out of your pocket. 

Everything Ken said plus plaster walls, no insulation, higher electric bills, walls sweating when its humid in florida and the resident leaves front door open, damp smelly houses, Pealing paint, wood rot, old windows, crawl space under the home, bdrm and closet doors that don't close properly, electric locks that the old front door doesn't like as the door is not aligned correctly, Cyrstal knobs that fall off, old thermostats with 2 lines but my new thermostat needs 3 lines, critters in the fireplace....

Ian I know your super heavy in the space.. do you have any of the deals your invested in or your club is invested in that are doing cash calls or worse going under ? 

They did a fantastic job with my cabinets and kitchen island, making my space look fantastic.