I found a thread that may be of interest to you, although it does not go into all the specifics you may need, but that could be a good starting point: ¿Puedo cobrar mis productos o servicios en bitcoin? (in Spanish, which I believe is your native language). You need to tie not only the platform/system to receive the payments, but also the tax/legal side of things ("nuestra querida hacienda").

I had a look to see if there was any hotel booking software that I could load using Softaculous, but I couldn't find any. I did find this site which compares 7 free CMS though.
https://blog.capterra.com/top-free-and-open-source-hotel-booking-engine-software-solutions-compared/

btw - I may have some good .com domain names if you need one.

You don't have to receive the money in fiat, but you may need to convert it to fiat to pay suppliers etc. You can receive Bitcoin into your wallet, and only convert it when you need to make a fiat payment. In view of the current relationship between Spain and the EU, and the overhanging collapse of DoucheBank and the Euro, you may feel that a holding in Bitcoin is a useful security. However, you should be aware that the price of Bitcoin is extremely volatile, and highly manipulated, and subject to users and speculators emotions.

You'll need to first of all learn of the pros and cons of accepting the bitcoin as payment based on its volatility and the possibility of incurring a loss
Bit accepting the bitcoin also which has a possibility of rising at any moment could also be a sort of good investment for you,and for your busines
You could store the bitcoins in your wallet,that way they still remain digital(bitcoins),and convert only when necessary(probably when you wish to pay suppliers as you said)

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