Longer Ron
at MTOW speeds the door and support structure are going to take a hammering
The door opening is scheduled with airspeed to help with adverse flow and the drag it inevitably causes when deployed. If you are doing a STO, and therefore using the lift fan, the sort of MTOW speeds we're talking about won't cause the hammering you suggest. They will be around 100-120kts - the lift fan door deploys at a much higher speed than this when decelerating from conventional flight into the hover for instance, so it can cope with 'airspeed' loads quite well. I'm sorry but I can't remember the speed limit on it now but it has a good margin. To put it into perspective, unless you are getting airborne off the QEC or doing a STO for periodic handling currency at home base (not the hardware store) you wouldn't routinely deploy the doors and engage the lift fan; you'd take off and land conventionally like a Tornado, Typhoon or F/A-18 does day-to-day.
The point of the extremely well-designed flight controls is that currency requirements for F-35B in the hover or for STO are not akin to the VSTOL handling requirements needed on the SHar or GR7/9 where a lack of recency/competency would result in a near or actual death experience...