Well, I finally managed to finish the first of the placemats last night. It looks quite lovely, though it has a ruffle on the outer edge, which I am not sure if it needs to be blocked to get rid of it, or if the pattern should be modified. In either case, I will make one more just like it, then I will do a set of four with a slightly smaller hook, either an H or maybe even a G, and decide whether to follow the pattern exactly or modify slightly. I think that in row 9, if I did only 2 dc in each of the end spaces, that would fix the problem without significantly impacting the rest of the design.
In any case, here is the finished placemat:
