Painting Beams To Look Like Wood

I have an interesting project this week to paint two large fabricated beams to look like wood.  Might sound a little funny to paint beams made of wood to look like wood but idea is to match the beams to the flooring below them.

To make the job more a challenge the beams were constructed in a ceiling niche.  They are each about 24 inches high by 15 feet long and 6 inches wide.

The first step was to fill all the nail holes and caulk the seams along the ceiling and sides of the niche. Then I primed the piece.  The white arrow in the photo below shows where after I had primed the beam part of the top ply of the wood used separated and I had to cut it out and fill the cavity.  It happens.

The primer is grey and then I am applying the base coat of paint to the beams in photo below.  Before I put the base coat on I have to sand down the beams.  When using raw wood the fine grain will 'raise' some after it is first painted with anything.  Then you have to sand down the grain that has lifted to make the surface smooth.

 A huge obstacle is the light fixture that is already hanging between the two beams as indicated with red arrow.  I could barely reach up between the two beams and prime them with that fixture there.  I have no idea of how I am going to create a wood grain on those sides of the beams but I might have to have the light fixture taken down.

The next two photos show the first side I created the wood grain look on.

This next photo is a shot of the flooring I am trying to match the wood to.  I am not trying to match the coloring exact just the look of the grain.  The beams are darker which is the plan.

The next two photos are of the other beam on the outside of the light area.  I will next try to paint between the beams and hope I have enough room to get in there to properly work the space to create a good wood grain.  If not the light fixture has to come down.