Something that I see I will have to deal with (and would love to get a little feedback on) is that he seems to be a touch gate-sour. This is something that I habitually go to some lengths to deal with before it even starts -- we NEVER end a ride at the gate or the barn, when I even smell a hint of stickyness near the gate we spend some time working at a good trot in the corner by the gate, etc. However, working at the trot today, when we come around the last corner before the one with the gate, he comes above the bit and I definitely lose his attention. Happens both directions, but going clockwise is the worst -- despite my best attempts to catch him and prevent it (half-halts, verbal "eas-y", focusing on trot rhythm), he inverts, drops his inside shoulder, and turns a fairly balanced turn into a hopping, jiggy, half-spin mess that I can't relax him out of until we're at/passing the gate.
I honestly didn't dare the canter -- if he's trying to turn a relaxed trot into a canter in that corner, I can easily bet that a canter will turn into a barrel-racer bolt to the gate, likely with a couple of bucks for good measure. That's honestly not something that I'm comfortable riding through at this point; my confidence is already a bit shakey after a couple of good tumbles last summer.
What I did do was lots of walk/trot/halt/rein-back transitions, doing everything I could to keep him relaxed and in trotting rhythm through trouble spots, also bringing him down to a balanced walk before he could take it upon himself to go into a sloppy, hollow, fussy "lope." My usual "fix" for gate sourness (working hard close to the gate, resting away) basically only seemed to frustrate him and exacerbate the problem. Near the end of the ride, I started focusing on making sure that I had his absolute and undivided attention at the walk -- every time I felt even the slightest lack of attention at the walk, I brought him into either a TOF, TOH, volte, or a balanced turn on center (keeping him on his toes) until he relaxed and focused on me, and then went back onto our circle at a stretching walk. That seemed to do a lot for him at the walk, and I ended the ride on that good note.
Any feedback on my "plan," or other ideas, would be most welcome and appreciated. If my "find and fix holes in walk" plan doesn't show results in the next few weeks, my next idea is to see if my considerably bolder sister would mind hopping aboard and just pushing him through it. I'd much prefer to work through it myself, however. I know that some of this (probably a lot of it) is a confidence issue on my part, and I'm working on that as best as I can.
Thanks in advance... and sorry for the small novel...
Hope everyone else is having a lovely spring, and is making it through Spring Fever unscathed!! 
