Concealing led strip light power supplies in a porch ceiling
Normally you have to install a receptacle face down in the ceiling and plug your devices in to that. For example, ceiling mounted projectors, garage door openers, stage lighting, all have to be plugged in to ceiling mounted receptacles. Not hard wired.
Concealing flexible cord above a ceiling is not allowed by the National Electrical Code.

400.8 Uses Not Permitted. Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following:
(1) As a substitute for the fixed wiring of a structure
(2) Where run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors
(3) Where run through doorways, windows, or similar openings
(4) Where attached to building surfaces
Exception to (4): Flexible cord and cable shall be permitted to be attached to building surfaces in accordance with the provisions of 368.56(B)
(5) Where concealed by walls, floors, or ceilings or located above suspended or dropped ceilings
(6) Where installed in raceways, except as otherwise per-mitted in this Code
(7) Where subject to physical damage

Note number 2.
There are other ways to conceal your equipment such as building a cove along a wall.
I just bought some 120volt LED rope lighting that can be much longer and doesn't need a power supply. However, you still can't run it above the ceiling.
Good luck!