November Wedding Garden Arbor

Our only local cousins oldest son Jeremy is getting married to Natalia (who is already part of the family) in just less than one month! I asked them what they would like me to make for them as a gift and instead of some piece of indoor furniture, they came up with the idea of a garden arbor - that they will be married under! How fun is that? The only picture for this post is a simple illustration of the basic frame of the arbor / arch. Five feet wide and four feet deep, it will be the perfect size to frame the lovely couple and minister, and a garden bench afterward. The design is Jeremy and Natalia's - I just had to figure out how to fit the bits together.
Details of this Arbor:  The arch joins the uprights smoothly, rather than with overhangs like some.  As they are getting married outdoors, the arbor will disassemble into 3 pieces (top and two sides) for easy transport.  The sides and top will be composed of lattice over the frame shown, with an arch-topped "window" in each side.  The middle rail on each side will support a flowerbox, also decorated with hearts. The lowest side rail is slightly above the "feet" to keep it from ground contact.  The top rails abutt the bottom rails of the arch. 
I was looking at different ways of joining the arch to the sides and have seen a number of relatively simple ways, from overlapping wooden joining plates to metal straps.  My first inclination was to join the pieces in some hidden fashion, both for appearance and to prevent places for the ubiquitous rain and dew to catch and aid in the decay of this structure.  What I came up with is shown.  The rails themselves will be joined by screws from the bottom side of the top side rail into the bottom of the bottom rails of the arch, so no wooden patch plates or Simpson Strong-ties will be needed.  So a nice smooth appearance. 
The fasteners are stainless steel, the lattice is vinyl and the wooden frame is treated cedar 2x2s, painted white.  Exterior construction caulk to keep rain out of places it shouldn't be.  The side flower boxes are cedar. Construction begins this upcoming Saturday.