#2 on Jason suggestion of the Lidl scaffold hoist and swing arm mount. Put one in my loft after the extension and new roof work and it works a treat. Helps that my loft hatch has about 4ft square of clear hole. If you re going to do job do it right I say. Disadvantage of the scaffold hoist style is that the pole needs to go above the swing arm so it all gets rather tall. Which may make a portable system impractical.
Used Penny and similar swing lift crane assemblies come up fairly frequently on E-Bay. Sometimes at sensible prices.
Unfortunately these things are all rather heavy. Heavier than a chuck so the whole thing may be a non starter for that reason alone. One of my slow time, back burner, projects is to modify one of the fold up convertible sack barrow / flatbed cart thingies to carry a demountable crane now I'm getting a bit past the age for swinging a hundredweight or so about. I figured maybe one of these :- **LINK** with fittings to clip a Penny swing lift style crane on when needed might do the deed. Obviously some sort of stabilising outrigger will be desirable and the crane will need suitable wall mount storage so its at the right height to just drop on. Nice won't be simple!
If its just chuck mounting or similar reach over the bed issues perhaps a sling device incorporating one of the common, cheap, ratchet tightening straps hung from suitable strong point or rail above the machine would suffice. Not fast but compact and inexpensive. An option I'm considering for my big lathe. Would be used with a sliding carrier on the bed incorporating a device to hold the chuck on centre height to easily plug into the D1-5 mount.
Clive.