Ok, time for an update, finally got the pier installed and now need to sort out the wiring, etc. I have an extra waterproof bag going over the whole unit for extra water protection. I also have an extra plastic plant pot saucer to stick to the top of the base, which, when upside down fits inside the bin perfectly so will provide an extra seal for the bin to sit down on.
Longer term I have a plan to add a shed around the pier (although new houses being built nearby so waiting to see impact from garden lights, etc. Went for the upside down bin method for the moment. Everything has gone well although my polar alignment for the azimuth bolt has shifting during build (though I had it bang on) so wondering how much adjustment I will get with the mount azimuth setting screw to get alignment? Otherwise I will rotate and drill/tap and new screw.
I will have a AZ EQ6-GT mount on the pier. I now have space in the garage nearby to start setting up the equipment, PSU, etc. I have a Redcat to learn how to use for astro and a Celestron 8SE for planetary.
Thanks for help so far.