Look'n good!!! I built a 3pt splitter a few years ago. Great satisfaction in a project like this!!!
You definitely have enough oil storage. I overkilled mine too. Had a 19 gallon tank. Put in 15 gallon of oil. Could have saved space with a smaller tank. Not sure how much force your splitter is going to develop but always plan big.
Also, might consider the location of the valve handle. Looks like you will have to reach down or maybe even bend down a little to reach it. If so, you'll get tired of that real quick. I built a bracket over top of my cylinder so my valve and lever was sticking straight up over the cylinder. Once I placed a log on the beam it was natural to lay my hand on the lever to activate. Doesn't sound like a big deal until a couple hours into splitting, then it's a huge deal!!!
Its hard to see in the pics but the splitter is actually quite tall. I am 6'5" so i built it to fit. The valve is pretty comfortable at waist height. Its a work in progress, but looking like a splitter now. Thanks for the reply!