When you say he walking better after a trim, it suggests to me that his trims are too far apart.  If you are going to start jiaogulan I would make sure he is trimmed every 4 weeks max. 

To me it looks like his toes are too far forward, especially if these photos are post-trim, and especially on his fronts (particularly the RF, which is actually not doing a good job at trimming itself given the dished dorsal wall and toe crack).  They might look good from the sole view, which is probably your farrier's only view, but the lateral shots tell the truth. 

Before putting him on a trot regimen I would work on getting his toe breakover back more, otherwise the forced trotting will put strain on his joints and soft tissues, as well as the lamellae in his hooves.

--
Kirsten and Shaku (IR) - 2019
Kitimat, BC, Canada
ECIR Group Moderator
Shaku's Case History
Shaku's Photo Album