So if this is raw land here is sales contract..
I suggest you ask for $1k earnest money and you can set the closing date for June, 2016.Thats reasonable for holding the land off the market.I would use local title company and they can deposit earnest money with title company.You are likely going to need a new survey if it hasn't been surveyed in awhile.You could do thin between now and June, negotiate closing costs here, that needs to be in the contract.
Locate title company have them review and send sales contract and tell you whether a new survey is needed.They will send contract to buyer and receive earnest money and hold it here.This can be done even if he is at sea, they get mail in most cases if it is a surface ship, or it can be emailed to him for signing.
This is the standard sales contract used by realtors here in Texas and would be recognized by a local title company.
Stewart Title is a large national company with branches all over Texas if you need an example.
I appreciate the chance to help you today.All closings these days are by mail or email and you can do this remotely if you need to.
Title company when time comes needs your bank account to wire funds after closings.You get your money within 24 hours after closings these days.