Seems that pulling the mast down via the main halyard would put a lot of stress on the tabernacle. Should this be a concern??
I don't think so. First, the force that you apply at the top of the mast is only a fraction of force from the weight of the boat, due to the length of the lever arm.
This force gets taken up by the stay on the far side (tension) and the mast (compression). (The near shroud will see less tension as the mast is pulled sideways, therefore, the mast compression to compensate for that is no longer applied, and can be subtracted. The total increase in compression is a bit reduced, as a result.)
If you draw a quick diagram, you'll see that at 45 degrees, the compression force is roughly double the force at which you pull from the halyard. So the load on the tabernacle shouldn't be excessive.
That was the long answer. The short answer is that this exercise is similar to sailing in winds that would heel your boat to 45 degrees (assuming a weightless crew). This is equivalent to sailing flat in the same winds with real crew hiking. You know your boat can take that. The only difference is that when you pull on the main halyard the entire sideways force comes at the top -- instead of being distributed along the length of the mast.
This puts an additional bending stress on the mast at the point where the stays meet the mast. (Especially, if you don't have the diamond stays). Because the mast is so long, the sideways force needed to tip the boat should be so little that there's probably no cause for concern.