I want to try perspective control and I'm good with using film (large format too) or digital camera (full-frame) to do that. What is the most compact option, which can be used while traveling?
Kipon make tilt shift adapters for SLR lenses with various mirrorless mounts. I have an Olympus OM -> E mount tilt shift adapter from them.
Olympus's OM SLR lenses are incredibly compact, so pairing one with a NEX body gives a very compact tilt-shift package.
Here are some examples of the adapter on an A7R with 21mm and 50mm OM lenses:
With the A7R being full frame you can only tilt the lens, the image circle is not large enough to shift. However if you use an APS-C body you will be able to tilt and shift.
Here's a size comparison of the setup versus a Canon 5D with 50mm lens:
The NeinGrenze 5000T point and shoot digital camera is probably the smallest option out there. It is specifically for selective focus to achieve the "miniature effect" and is not going to give you full control of either tilt or shift, although it has some tilt control I guess.
Another option would be a Lensbaby lens such as the Composer Pro. Again it is not a true tilt shift lens but can give you the effect of out of focus areas if you are going for that. Much more information is given in the question I asked earlier here: Can the lensbaby achieve a similar effect to a ± 8.5° tilt?
Finally, if you do want both true tilt and shift movements, you might just have to go all in on a SLR lens such as the Canon TS-E 24mm f/3.5L or TS-E 90mm f/2.8 which both clock in at around 20 oz and roughly 3"x3.5". If ultimate compactness is your goal, you could attach it to the Canon EOS M with a EF adapter, or to the full size APS-C Canon SL1 without an adapter.
Beyond that, I'm not sure of anything that is truly compact.
I created a blog post that outlines all of the movements of the Canon TS-E 24mm L that you might find useful: http://photo.blogoverflow.com/2012/08/tilt-shift-lenses-for-portrait-photography/
Movements of the TS-E 24mm f/3.5 L II:
- Tilt Lock
- Shift Lock
- Lens Rotation Switch
- TS Rotation Switch