Using the bladder technique very high pressures can be achieved without recourse to an autoclave. My compressor can provide 10bar of pressure, which is enough for most people :-)

If I do try the bladder, I would like to do it in a way that I have a back up plan if it leaks. Maybe a few premade bladders, have a layer of release film between bladder and lay up so if it pops I can quickly pull it out and stick another one in or something like that. Or just stick subsequent bladders inside the failed bladder. From my understanding though, the bladder needs to be fully encapsulated to handle the high pressure. Can't just be an open ended tube, mold needs to be closed at both ends with probably a half spherical shape and a smaller hole to insert bladder into. 

Another question on this, could a compression mould work? Male mould milled smaller by calculated wall thickness, wrapped in lay up (makes use of sleeve easy) then drawn into female mold with plenty of pressure to consolidate layers and squeeze out extra resin. Currently the ends are the only areas without taper, but I can adjust the design to have a slight taper at least on the inner wall to make removal easier. I would think this would make the lay up process super simple and make an excellent part that has great consolidation and a smooth finish inside and out.