Hi Julie!
Here in NC, a draft horse "sledge" or sled or drag or ??? (and even the Otter sled) can be used w/o shafts on the sand and even in the grass - especially on the flat. Down hill on grass or mud - either shafts or not on the hills at all. On snow (slick and slidey or icey type conditions), I'd definitely want shafts (or again, not on the hill or packed/icey snow at all). Even where you are at, I'd think if you loaded it with wood that you are moving around, Spankey could pull it up/down hill w/o using shafts. I suppose I could be wrong. And yes, it's my understanding that the Otter type sled works really well in mud.
I, too, liked the link that showed how to hook up the shafts. NEAT.
I've been looking at an idea to use a tongue for the Otter Sled BUT think that the sled itself is too small/light for our ponies to pull as a pair (off to the races - as in charioteering!).
Here are 3 pics of the draft horse sled Bell & Bit pulled - and with a much larger "tiny" Belgian and an even larger Belgian...
RR - forgot, I can no longer attach pics to this forum.... GGGRRRR...
OK, well you can see them at these links - All 3 of these taken in 2010.
Tiny
Bell and Bit
Rex & Belgian (s) - and it's a PAIR pulling it!! I remember how well the girls (mine) did when pulling it - it scares me to think of this pair pulling it!!