I haven't found anything yet that 27 tons wouldn't split through with a single wedge , I seem to split a fair number of knots.
I have a vertical / horizontal splitter , while it isn't a high speed production splitter , it is very versitile the big rounds I often roll the splitter to them and flop them into the splitter with the beam vertical then wrestle them around a bit , a cant hook can help turn them then take another bite , taking another chuck out of the round , I might get 4-8 chucks then go back and split them or toss them on the trailer or truck to bring home and finish splitting.
a single wedge 27 ton is going to be a hole lot faster than by hand but not a high volume production unit like a box wedge type that can split 4-5 split son every pull
but if you don't have several thousand in your budget my 27 ton was 1500.00 new
if you really need to go low budget , you can do like we did when we got started have a big stack of rounds and rent a splitter for a day and switch off and marathon split till you have to take it back , don't stack , just move the splitter down the row of rounds keeping the person running it fed then switch.
I do not miss a weekend of splitting form 7:30 am when I could get the splitter home from the hardware store till 9 at night then start splitting again at 7am till 8:45 then hitch it back up and have it to the store as they opened at 9 on sunday.
it sort of depends on the size of your cotton woods here they range form 8-10 inches on up to your going to need to cut from both sides with a 24 inch bar and might find a few that need a 32 inch bar from each side
what are you burning in ?
what is your time line to split it ? 10 cord a year as you burn it or 60 cord this year
not sure how big your covered back porch is but 60 cord stacked 1 cord high would be 1920 sq feet about the size of a hole house larger than my house ,cotton wood is also nearly twice as heavy wet than dry , making it one of the heaviest woods when wet and lightest when dry