Thanks for your excellent analysis. I'm inclined to think May 3 is the accurate date too, but April 27 in the one article got my attention and is a head scratcher, as is the date on the thread.
I think Jubal probably showered at work after his shift, but after wondering if the On the Bayou RV Park could be where Jubal showered, etc. I looked it up. I've stayed in a lot of RV parks in about eight years of full-time RVing back in the day. This appears to be a well run facility, and I doubt they would knowingly allow a guy living out of his truck to bathe or use the restroom there daily. There is a restroom in the main office, so I suppose he might get by with that occasionally. However, if he had a friend staying there, he could have used the shower in their RV without a problem. They do rent spaces on a daily, weekly or monthly basis, so there could be some workers living there. But if a friend lived there, wouldn't the friend miss him before May 3? Or perhaps the hypothetical friend thought he had gone home for a few days.
http://www.onthebayourv.com/rules--regulations.html
I'm sure LE is also checking to see if any fellow workers living at the RV park could have had it in for Jubal.
I've stayed in RV parks where they will permit people not renting a space to use their showers for a small price.
I think it's possible that other contractors at the plant could have been staying at that RV park. It does look like a nice park and it is close to the plant. I haven't looked around the area to see what other RV parks are close by, but I suspect there are probably others considering the petrochemical industry and the wildlife refuges.
I think it's also a possibility that the plant had locker room facilities with showers.
I get the impression from some of what his father has said that maybe his son hadn't been working at this location for very long. Not sure about that, though.
As you said, we're still left not knowing when his absence/disappearance was noted by coworkers and/or friends.
There's a photo on some of the news reports of his pickup parked under the FM 2004 overpass. Going by the maps, the boat ramp is located on the west bank of the bayou, whereas the RV park is located on the east side.
The bayou "looks" to be navigable down to the bays off the Gulf of Mexico. Likely is is also navigable in the other direction, but who knows how far. I'm not a boat person so I wouldn't know where to look to determine that information with any certainty.
The May 13 reports indicate that the search for his head included searching in the water.
I suppose it would be possible for the assailant(s) to have arrived/departed by boat.
The "why" of a deliberate decapitation seems almost beyond comprension, much less the "how," the "where," and the "who."
The "when" would almost have to be during daylight hours if it occurred between his shifts, or at least an abduction during daylight if for some inconceivable reason he was killed elsewhere and his body and possibly his truck were returned to that spot.
Incomprehensible and inconceivable to consider.
Deliberately so, or an act by a totally crazed mind?