Ignore what I said in the first post.
Sometimes I'm a little slow on the uptake.
Clamp a straightedge on the long panel, so you can cut the scarf
apart with a skillsaw set on the proper
slant (with scarf attachment in place). And then reglue
the joint, following the instructions for wetout, filler,
clamping etc. You might have to cut twice, to get two
clean, gluable surfaces. I would try to do it with one
single cut, right through the scarf. If the resulting
surfaces are messy, with hard plastic glue showing, rather
than clean bare wood....then cut two more times, trimming
each end back about 1/16"
<img src=/scarfing/scarfing2.jpg>
<img src=/scarfing/scarfing3.jpg>