Sounds like you are going to have fun with Skeeter!
I'm another who uses c/t - and the good thing is you can look at lots of different "approaches" and then see how you can chunk them down, and use the clicker. Freeshaping is an excellent way to start ( as IW will testify

).
I have been playing with a mattress ( put an equimat on top and you have a really boingy surface - fab for their balance and core stability). Freeshaping ( ie clicking whilst at liberty for tiny approaches etc etc) is great - and gets them to really love what you are playing with. - And while I am writing this I have just thought how to break this down - Lottie my hipo found the mattress really easy. CAllisto is very tentative - she puts a foot down but then scares herself , not when she is pressing her foot down, but when her foot comes up with the boinginess and leaps off. SO am going to go and find a pillow that can go horse training!!
I do want to see Bea Borelles trick training dvds - she uses treats ( but not clicker ) _ she is Phllippe Karls partner - I read in an interview with her that when he was away teaching the good thing was she didnt have to put her toys away in an arena!
Imagineahorse may also give you inspiration on what to do - but then you can decide on how to do - I know some do not like his approach ( but all his horses love liquorice, and he sets up the environment very carefully so they can be successful)
Alexs latest dvd shows how you can loop behaviours together, and discusses hierarchies of reinforcement - how one fun activity can reinforce the next etc. Havent watched it all though , ( it is nearly 7 hours long) and am just listening to how Bob Baily ran his chicken camps .
C/T doesnt have to be done at liberty - but I think it is a really good starting place. Horses often try and please so I think it shows ones timing up much more, as one gets what one teaches ( they used chickens to teach the mechanical skills as you get exactly what you train with a chicken!!). And your horse has an option to walk away.
With the freeshaping and c/t it is often best to start with something ( though sounds like you are already doing this) completely outside his "behaviours " already. eg Teddy targeting being a great example. There are then no negative connotations attached already. and trick training , blowing horns, choosing colours etc also fall into this category. If Skeeter loves to do one of these, then you can powerwalk in between , and then he gets to go do his favourite activity as a reward for his powerwalk or suchlike.
Enjoy!
Hilary ( I have a United Nations beret ( the blue one) from a previous tour - is currently sitting on my head

)