You are planning a BIG mistake. 

Getting a DOT number only requires applying and then filing a form once every two years.

You will need an IFTA to cross the state line.  That requires mileage and fuel records and filing a report every quarter, along with paying the tax due.

You will need to file and pay the IRS 2290 tax. 

You may need to run a apportioned license and keep records for that.  That will depend upon the state reciprical agreements for a farm license.

You will need to join a drug screen consortium.

You will need to obtain a DOT medical every two years.

You will need a DOT inspection every 12 months on your truck and each trailer you pull. 

You will need a maintenance file for each vehicle and a driver file for yourself and any other driver.

If you start with your plans and fail to do any of the things I have listed for you, you will likely find your operation put out of service on the side of the road somewhere, and a summons to court for the purpose of paying a fine.  I would do it right and avoid the risk of the latter.  Your insurance rates will be higher if you have violations on record.