John, sorry to hear about your problems.  Here is a shot in the dark.  You
mentioned you changed your oil and filter before the flight- you did not
indicate whether you had any oil problems before you changed the filter.
Filter internals have been known to collapse or otherwise obstruct oil flow.
Impeded oil flow could account from both the low pressure as well as the
high oil temperatures.

If indeed these problems did not exist before the oil change -I would
strongly suspect the only new component in your oil system - the oil filter.

FWIW

Ed Anderson