I’ve not tried the paving slab route but when i looked at (and did) this same thing, those mesh grates that you pour gravel into were an easier option.
I put an Asgard half on compact dirt and half on paving slabs, it was there for 2~ years and was fine. It got taken down because it was a rented house (not because after 2 years it suddenly became not fine)
I’ve not tried the paving slab route but when i looked at (and did) this same thing, those mesh grates that you pour gravel into were an easier option.