You will be way happy with a 4 inch splitter (20-25 tons, depends on marketing BS).
I have a 4 inch with log lift and feet, and it plenty for anything I can physically handle by hand (no skidsteer)
"If your gear is never too small, it is always too big"
Not saying you want a 3 inch like I built below, but 4 inch should be way plenty unless you have a woodlot or landing and do a lot of big stuff.
cut and paste from my files
I built a splitter last year that totally goes against the 'biggest, baddest, splits anything' grain.
I burn wood for about 70% of my heat. I also volunteer with a charity group that cuts and splits firewood for needy families. I have a shared 4 inch splitter that I built covers, folding log lift, and folding outrigger feet. It does big stuff, but is stored off site due to my small lot, and it is not easy for me to use for small scrounges, nor do I have an open trailer to haul it to the charity cutting.
I have used many splitters over the last 25 years and my main complaint is speed, very rarely force. My goal is the maximum amount of wood in the trailer in the minimum amount of time. I prefer to cut and split a trailer load of medium sized wood at a time, in the woods, and leave the mess and noise there. I would like a lighter splitter I can store at home, take with me to the woods, work rapidly, and bring home.
I have no ego problems admitting defeat, and I just leave the big rounds or twisted crotches in the woods, rather than spend a lot of time and sweat and muscles fighting them. I will get more wood per day and not worry about the 2% condition where the ram is too small. Those who brag 'there is nothing this one can't split' really mean that to handle the 2% monster rounds, it is too big and slow for 98% of the time. There is an old saying: "If your gear is never too small, it is always too big."
My original intent was to find a small splitter that could mount for travel on a receiver hitch on the rear of my trailer, to handle everything in one trip. Brave EZ Split, older Sears Craftsman, and Bachtold Brothers made really small and light units, but were single stage pump and WAY too slow (20-25 seconds).
My goals
1. For homeowner, wood scrounger use, not heavy duty wood lot use.
2. For wood diameter about 18 inch maximum (the largest I can lift or handle), and 16 inches long.
3. Want maximum speed, maximum mobility, and minimum weigh.
4. I don't want the biggest, meanest machine. I want the most wood in the trailer in a day
5. A 3 inch cylinder and 8 to 10 tons is sufficient for what I need.
6. Must be a two stage pump for maximum speed.
7. Minimize the hydraulic system weight, size, and heat generation by good design efficiency and a specific de-aeration spiral reservoir design.
8. Mount to receiver hitch, ideally for use but at least for travel, to move everything in one trip.
9. Good ergonomics for my aging body: good height, not bending my back, natural valve location and operation, minimize trip hazards, good input and output tables.
10. Quick to assemble or knock down with no tools, minimal or no loose parts, easy to move around, and should stand upright for storage taking minimal floor space.
11. Any single piece is to be portable by one person, either by wheels or by physically carrying.
CRITIQUES THAT I GET
1. 'Too small to do the massive rounds I get'. True. See goals 1, 2, and 4.
2. 'Too lightly built. My big rounds would crush that machine.' True. See goals 1, 2, 10 and 11.
3. 'Tank is too small for the 'rules' for 13 gpm flow.' Nope. Professionally designed to meet goal 7.
4. 'It will overheat.' Nope. Runs hot on hot days, 80 F over ambient, but adequate hydraulic practice for as hot of a day as I wish to work firewood.
5. 'Costs as much or more than a box store 4 inch splitter.' Definitely true ! Most major components cost the same regardless of splitter size, especially when purchased one at a time. It costs money to get to goals 10 and 11.
I am a retired mechanical and fluid power engineer. Eventually, I designed and built a portable 3 inch diameter splitter. It is designed to break down and all pieces be hand carried or loaded by one person, to be set up quickly for portable use, and for very fast ( 6 seconds out and back) operation on wood under about 18 inches in diameter. It all fits into a receiver hitch cargo basket for transport. The beam stands on end for storage.
DATA
Force and power 3 inch cylinder, 20 inch stroke, 2400 psi, 8.5 tons max.
Speed About 6 seconds full cycle at 1.9 tons
Production One person, 3/4 full cord per hour. 3 persons, 1 full cord per hour.
Heat 80F over ambient. 165 F tank on 85 F day.
Layout Moving wedge, 6 high, plus 3 inch secondary, 26 degree included angle
Beam 6 x 4 x 3/16 rectangular tubing, reinforced, 36 inches off the ground
Engine Honda 160 cc engine, salvaged, on vibration isolators.
Pump Haldex nominal 13 gpm (0.192 + 0.647 = 0.849 cir) Unloading 500-600 psi.
Valves Prince relief valve on power unit about 2600-3000 psi
Prince spool valve, RV 2400 psi, detent and kickout on retract
Tank Custom made, spiral de-aeration design, about 2-1/2 gallons.
AW46 petroleum hydraulic fluid.
Usual accessories Return filter, spin on 10 micron. Sight gauge/thermometer, fill cap.
Conductors SAE 37 degree swivels, -08 (1/2) inch pressure hoses, -10 (5/8) return
hose. -16 quick couplers.
Misc In and out tables, quick detachable wheels, no-tool assembly.
Tripod leg design. Stows for travel on a receiver hitch cargo basket.
END