You're talking about the Icom M700 PRO, not the M700 which is a much older rig that was the standard for awhile. It sells used for about $400-600, but doesn't have the flexibility of the newer rigs.
Yes, you need a tuner. No practical way around that. Figure another $300-500.
And, if you're going to use an end-fed antenna like a backstay or alternate backstay, you'll need a good RF ground system as well.
Andre....I, too, think you've got far too little time to prepare a new-to-you boat for a 10,000 mile trip. The radio will be the least of your worries.