I am a career firefighter down here in Florida and I do tree trimming and removal as a side business. It's hard to call it part time as I do quite a bit of work. I mostly work alone, or with a helper for a ground guy. I've recently decided it's time to get a CUT/SCUT tractor to help with loading brush and logs and maybe doing some occasional brush hogging and loader work. For the most part, however, the tractor will live with a root grapple on the front.
Greetings Brother. I'll say welcome to TBN anyway even though you have been a lurker.
Here are my thoughts on your question - some you may not like or want to hear.
First of all I think you're on the right track for tractor size given what you want to to. You're not in the logging / timber business you're in the yard clean up business. A small SCUT will carry and move more than you can by hand in a shorter amount of time and (most importantly) saves wear & tear on your body.

And I think that's pretty much what you're looking for as I understand it.
I would suggest you look at a flail mower instead of a rotary cutter - especially if you're doing more urban / residential type work. A flail is less likely to send something flying thru a neighboring yard (or window) and since you are doing "for hire" work there is always liability to think about. There are threads upon threads about flail mowers and quality of Chinese vs Italian vs whatever else for the price so I'll let you wade thru those arguments on your own should you opt to go that route.
I would suggest you get something along a 4' w/ hydraulic side shift that will let you mow closer to buildings & obstacles than a rotary cutter. It is also shorter overhang off the back and makes a pretty good counterweight for your loader work.
Now - on to where I think you are headed for murky waters . . .
I picked your leading choice for some rough numbers.
Mahindra Max26XL
Tractor 1863 lbs
Loader 627 lbs
Liquid
Ballast 47 lbs/Tire (Assuming Industrial Tires)
Rough total 2584 lbs
I looked for a good bit and most 6ft wide dump trailers stopped at 10' and the majority of 12' long were 7' wide but I did find a couple 6' x 12' to grab some rough numbers on and the trailer Tare Weight was ~2500 lbs and up.
So now you're looking at 5084 lbs without any implement weight (i.e. whatever mower you pick). You also have to factor in the weight of ALL your other gear, tools, saws, fuel, etc into mix.
You have 6400 lbs towing and 11360 lbs Max Combined with a truck that comes in at 4400 lbs and change depending on model & cab config.
To translate all that technical mumbo jumbo to simple English - you're pushing the limits of your trucks abilities and, safety issues of that aside, you're going to cause it to wear out components faster.
So now's the part you probably don't want to hear.
You have to decide if you're a F/T firefighter that does tree work on the side or if you're in the tree business F/T and a firefighter on the side (and trust me I know some F/T guys here that run some pretty big cattle / dairy farms and being a Firefighter 9 days a month is actually their side job).
Given the year model of your Tacoma I can understand you not wanting to turn right around and upgrade vehicles and that's ok. And I'm not saying that you should, but if I were you I would be putting that upgrade on my radar with-in the next couple years -OR- I would be all over craigslist looking for a very well used but serviceable 1/2 to 3/4 ton. A flatbed would be ideal as you could put implements, attachments, loader bucket (or grapple) on the deck & tow the tractor in the dump trailer as planned.
As a semi-related side note - I have a 1997 Taco Extra Cab 4x4 V6 that I bought brand new in '96 - I'm back to driving it again b/c my nice 2015 RAM is in the shop. Said Taco has 332K miles on it and the running gear is tight as ever & uses no oil so I know what they are capable of if you treat them right.
I wish you the very best what ever route you decide to take.