You don't have any Mandarin speakers around!? Where!!! Hahaha I've yet to find a place with no Mandarin speakers. Feel free to send me a message on discord if you want to practice.
As far as learning two languages at a time, I think it's do-able, it just takes an extra level of devotion and it may be a bit slower. I did French and Japanese at the same time but I was more interested in Japanese and so my French kind of fell apart. Really it's just about being able to motivate yourself to actually speak.
I've been thinking of going to more Mexican restaurants to motivate me to learn Spanish. It's not hard to learn a language when you aren't in the country, but it is hard to motivate yourself to keep studying when you don't have any chances to use the language so you need to create opportunities.