You may have trouble finding someone here who uses a Rokuhan Shorty controller. Even the full size Rokuhan controllers can be difficult with Marklin locos, due to controller protection cut off of older 3 and 5 pole Marklin motors with their slightly higher amp draws. So I suppose the first question is what type of loco will you run on your suitcase layout? If that is only Shorty locos I can’t see why it wouldn’t work.
A good dealer in the US who might know is the Zscalehobo, Frank, as he sells all this stuff and is very knowledgeable and a great communicator.
Also note that NOCH makes panel mount speed controllers. Frank would know if they are available.
But if it is a small battery powered controller you are looking for I would suggest the Blueline Snail Speed Controller. I believe they have panel mount and handheld models. They run on a 9v battery or wall wart, and have some great features, first that they are tiny, but they are not cheap, just inexpensive ;)

I have the RC03.

It is hit & run. Some locs work, others don't.
Some you have start with full throttle so the safety doesn't trip.

You can keep a list with locs run fine with it. The new locs sometimes start running with the minimal voltage rokuhan uses to get the lights working :)