Hello JAZZ, and thanks for your input !

Your design will be substantially weaker than what Jons suggesting and if you want strong and durable then it doesn't get much better.
Has for keeping the screws protected then that's easy enough with a bit of thought regards covers etc. The high sides don't cause any issues in use for most work and actually help contain the cutting mess to the table area instead of slinging it all around the shop.
The advantages of the much increased strength and far better quality of finish on work combined with allowing higher feeds is well worth the sacrifice of bit of access when loading material. End of the day it's the quality and speed of cut that matters.
now I'm sitting and scratching my head ..,
new design?, short as possible sides?, Z-axis below the level of the X-rails?, Hiwin rails 15-20mm?


Gytis