coloradotrout wrote:

the tilting idea is worthy; more surface area; that i need

i will have another look

The issue is my opening from return is right next to the blower unit.
I don't really have a way to tip the filter. It would tip against the
fan unit -- which -- I suppose could work, but just flopping there
loose.

I can visualize that. Do you have a downdraft and where is
the furnace?
If you have some space another option is to use two filter
held in a V, lots more filter in less space, but may be hard
to fabricate.

Another thought if you don't have enough space above the
blower is to simply put the filters in the cold air
returns. That would be practical and easy to fabricate if
you have 4 or less (and way more efficient for air
passage). Could be a real hassel if you have returns in
every room.