I was thinking about taking the mast support to a welding shop (or somewhere), have them cut it in .75 and .25 sections (leaving the .25 section bolted to the trailer), insert a sheaf so that the two sections could be connected and drill holes for a pin (similar to how removeable trailer hitches work). Sound like a good solution?

Any concerns about trailering at highway speeds? The internal sheaf could be fairly long and would need a cap on it.