PhilipG,
The KPP is being met. Achieving that was the main driver for the weight reduction programme, and it remains a requirement that can't be traded away.
Storm Shadow was, and is not, a weapon the F-35 (of any variant) is required to carry, let alone do a VL with. That would be beyond the bounds of physics. As I said in an earlier post, all combat aircraft have limitations on what they can bring back, even with conventional landings. A VL is the most difficult case, with just jet thrust to do the job.
The B can't jettison its pylons, they are hard mounted.
Hope this helps
Engines