The tinkers' options 
Hi Matthew,
Travel scopes can come in many shapes and sizes. But one thing still reigns in all designs - aperture is King.
Now, if you like tinkering, the options available to you are vast. You are then not limited to commercially available instruments, which can be limited in aperture capacity and come with a hefty price tag, but you can use surprisingly good inexpensive optics to make yourself a sensational instrument that is not only portable, but excellent mechanically.
I too love to tinker. This has led me to make several scopes, from just a new dobbie mount through to the whole hog of tube and mount (I draw the line at grinding my own mirrors
). I've attached a few photos of some of the things I've made that fit the brief you gave in portability and stowed volume:
1, 114mm table top scope that has a 500mm focal length. Such an instrument is usually best suited to low power due to the limitations of the shape of the mirror, usually being spherical rather than parabolic as is needed for high power, though sometimes you do come across such mirrors that are parabolic, and then you've really hit pay-dirt.
2, a 6" table top dob. This is a very good instrument and gives a fantastic image at high magnification. I've pushed this puppy to 300X on a good night and the image is a corker
Both of these mounts I've also made so I can easily remove the scope from the dob mount cradle and pop the scope onto an equatorial mount for when I need to. Best of both words this way,
These type of mounts are very easy to use.
3, 4 & 5, a 10" two pole scope that stows into its own mirror box and is the size of a small garbage bin when stowed. Very robust design that can take some punishment so you are not paranoid when packing it. Yes more involved than the above dob mounts, but not rocket science. Actually, this scope was my very first astro DIY project! I've still got it too, and when not in use lives quietly and unobtrusively in a wardrobe.
All of these instruments are very portable, and not difficult to make, mount or whole thing, have more aperture grunt than a small refractor Mak or SCT, for less money, and just as good optically.