The locations where you are going you should be fine if you stick to the places that are near BTS/MRT or in major tourist areas or where lots of foreigners frequent. If you link up with backpackers, I'm sure one of them will be able to point you out in the right direction.
But to actually answer your question, it would be difficult without some help to move around in Thailand. Especially non-touristy places. Many of the cheaper travel options require some basic use of the thai language, and minivans with destination will often be in Thai only. So with no ability to speak/read Thai or have a Thai friend with you, I highly recommend the Paiboon's ThaiDict (there is an iOS version also). It is the most comprehensive dictionary out there, complete with common phrases, ability to power search (search the word and the definition), explains the alphabet, numbers, basic grammar, classifiers of nouns, and has meaningful categories. Every word is spoken by native Thai speaker. $25 USD but after you are overcharged for a taxi or two or forget which stop to get off of, you won't blink twice to purchase it.
Use ThaiVisa's local forums section or Travel forums to inquire on potential destinations. But when you need to make on-the-fly travel decisions, it helps to be able to speak to local people and scope local scene. At least know the 'connectors' where you can take minivan or bus from one town to the next.
Add: I don't want to scare or spook people from traveling off the beaten path. We all have to start somewhere. Particularly a non-speaker armed with either a smartphone or tablet and internet access is still well ahead of the pack. Use short phrases (verb, subject, maybe an adjective here and there) and you will get by for most simple requests. Just don't be surprised if you find yourself traveling for many KMs and they only speak Thai....TiT [This is Thailand].