Doll trunk suit case thing

The only thing I know of right off is something like this
http://www.dollmore.net/shop/step1.php?number=4739

Though I don't think it could hold four 70s.
It will hold two 70s comfortably (and possibly two msds behind the two 70s if positioned correctly)

 

Dollzone used to have a red hardcase that would fit more than just one 70cm.

 

There are a lot of fashion doll suitcases/trunks, which may have been what you saw for the MSD size. (I've seen ones for Gene dolls, or American Girl dolls, etc. that would possibly be workable for tinies or MSD.) For something bigger, it'd be a bit harder. You may be able to find a suitcase to convert.

If you want it for less portable storage purposes, you could possibly find a cool old steamer trunk to adapt, though when I say 'not so portable', I do mean it.

 

I just use a suitcase on wheels which looks exactly like the one from Dollmore. I use the pillows the dolls came with to put them in then put them in the suitcase.
but Coolcat does some doll carriers and ebay might be a good place to look!

 

It does sound like a custom job..double sided trunk perhaps, and sounds fabulous I would love a trunk on wheels that I could keep them on one side and clothes on the other. Sounds like you could find a double sided trunk and modify it though.