One can do up a lot of firewood with an ATV, and from some pretty hard to get to & tight spaces.
That's a nice sled. You could even take it to another level & save some handling/steps by cutting to length right on it like a sawbuck. Might have to rearrange a little bit - I'd try first putting two long ones lengthwise, then maybe 4 or so short ones cross wise, then pile your load on those. Then when you get to where you're going, you can cut the load to length in no time. Might need a bit taller stakes - but having the load raised up a bit will get it further from your sled so your saw will be less likely to get into it, and will be a bit easier on the back. Should still be lots stable since your runners are outside the load a bit, and it still won't be very far off the ground.
I kind of poo-poo'd sawbucks until I started using them on a trailer. Cuts down on the time & handling big-time. I can haul almost 1/4 of a full cord on my trailer behind my ATV (in summer when traction is good), and can cut the whole 1/4 cord to length in 5 minutes with my ms360 + 20" bar.