It could work, provided that your violin holds its place without any excessive movement (more than 1cm or something like this). Otherwise, the suspension of the case, would not work properly, and your instrument could get damaged from a sudden impact. 

I know that there are some viola cases with transformable interior,  allowing the player to adjust the length of the body to match their instrument.

However, The main issue is the body of your instrument, because you could find violin cases without any accessory compartments near the scroll, and solve part of the problem

Maybe you could also be lucky with a case that stores the violin diagonally? like the Courier by Embassy, or the Diagonale by Gewa?

If you are in a hurry you could go diy (I had to do this twice, and I was lucky). Many cases are quite cushiony, and their main material besides the outer shell is some kind of polyurethane or polystyrene, lined with a silky or velvety textile. If you are careful, you could place a soft cloth over the lining, and then work with a hammer (or even your hands), to shape the case to fit your violin. Eventually you will get a 61 cm case (which is not a rare size) to something a little more comfortable. 

If nothing of the above works, then there is the option of custom made cases, according to the pattern of your instrument. (I know that Dimitri Musafia offers this option but it could prove expensive I guess, and you could also ask Negri and Riboni)

But I would go for the viola case if it holds your instrument firmly. There are many advantages, more accessory compartments, they are sometimes cheaper than violin cases

ElisaDalViolin said
Good news!

I've been working on my cheap chinese violin case with a hammer like Hermes suggested and after a couple of tries and heavy work, I accomplished to achieve a nearly good fit for my violin. I'm very glad that it's possible to somehow make it fit ( only if the body lenght of the case is 37 cm, no less, or else might ruin it with the excessive "modelling")  but my question is, by doing so is there any chance of reducing its protection from the weather/temperature variations? 

Glad that you made it!!! I can really remember this feeling when I made it work in the past.

The question refers to future "remodelling" or on the current situation? 

Anyway, if the outer shell and its canvas (if there is one) is intact you are as safe as you were before. Yes, technically if you remove a part of insulation mass of something you may reduce its capabilities, but I really doubt there was such a severe action on this particular case 

So if you have an intact outer shell, with foam interior and some kind of a velour, and then your instrument, I suppose it should be as ok it were before.

When it's really really cold I like putting my violin in a silk bag before storing it on the case. And for extreme conditions there are some supplementary "jackets" that you could wrap your case in them (especially if its a plastic, fibreglass or compound one)

You sound like someone that really cares for her instrument so I suppose that you already have a hygrometer and humidifier, just to keep you relaxed.

ElisaDalViolin said
Thank you @hermes 

The question was mainly to future remodelling (new case) specially because the german is more delicate instrument than my chinese Stagg. 

When is cold, I wrap the violins with extra fabric, a silk scarf and other made of cotton and I have a dehumifier in my room. My main worry is the excessive humidity and not the opposite, the temperatures don't go extremely low here. I'm trying to research the best option for me at this moment but the measurements,  the lack of them in the cases descriptions online and the lack of cases available in physical stores here are making it a bit difficult so the diy surely brought me some relief 

I see

So, get the largest you may find, in all aspects I guess. (more length, more foam to remodel hehe).

Wow, with all these fabrics, velvet, foam, plywood and canvas, I think that you will be ok when going outside, no matter how much you will have to press the foam

Good luck with the case-hunting!