Using Agri Exemption

This is an area of verbal diarrhea by the FMCSA and it has been forever. In multiple places they state that the driver must perform an inspection at the end of the drive shift for each vehicle that they drove that day (including trailers.) In another singular mention of the regulation they also state that "before driving" you shall make sure that the vehicle is in safe operating condition AND that you will review and certify corrected any PRIOR defects reported from a previous driver that weren't yet certified and fixed.
For this reason, many companies require both a "PRE" and "POST" trip inspection just to make sure they are covered. Conversely, I have worked with hundreds of drivers over the years who only did one inspection per day as well.
What I always recommend on everything HOS-related: "Don't give them any reason to detain me cuz I needs to be rollin' to make money brutha." SO, if I were you I would check my vehicle at the beginning of the day (remember you are on PC-Ag Exempt at that time) and I would stop and report any defects that would prevent me from safely driving right then through a paper or verbal report to my safety/maintenance department. You are not required to be on HOS at that time because of your Ag-Exempt, but you are still required to be operating "safely" as a CMV driver. Furthermore, if I did go outside of the 150 mile radius, I would also press the formal "inspection" button on the ELD itself while in line 4 (On Duty) and perform a formal DVIR at the end of the drive shift so that it gets recorded in your ELD history. Remember that on most ELD's it will automatically put you "On Duty, Not Driving - Line 4" when you do a DVIR inside of the ELD program.

Lastly, a reminder: When recording an inspection, use the "remark" box in your ELD time to say "truck/trailer inspection" or "pre-trip" or "post-tip" etc. Very often I see that someone is pushing the "DVIR" button and then recording "No Defects Found" without recording a brief period of "On-Duty, Not Driving" (usually 5 - 15 minutes) with a remark that actually reinforces that you were doing an inspection. Don't give them any ammunition I say.

Official Inspection Regulation link is here: eCFR — Code of Federal Regulations