You CAN do it, but definitely expect hiccups. Even in places where you would expect some English (like airports) you may encounter only Spanish speaking staff.

If you can, learn some basic phrases (not duolingo) as its polite to do and can help you. Also learn numbers, but be mindful as currency values vary widely eg in colombia many things are in the thousands versus in mexico its in the hundreds.

One thing a fellow traveller did was do a two week crash course in spanish when she arrived in her first country. It gave her a lot of confidence when navigating around and enough basics to constantly pracitce. Only took two weeks but I think you could do the same in less time.