Layer-3 Network Design with Nexus's and Catalysts 2960's?

Morning, All -

Currently working on a Cisco project to provide full redundancy for a network, and trying to determine the best design. Hoping to lean on the great knowledge pool here :)

This is the basic link topology for the section of the network in question. The Nexus 9200's at the top serve as the current network core, and the Catalysts are the access switches. We are adding the Nexus 9300 at the bottom as a secondary network core, physically redundant from the 9200's at the top. This 9300 also connects to our Colocation DR site with warm standby servers.

My question is a basic one - what is the best way to prevent network loops? All access VLANs must be available on all switches in this topology, so no selective trunking.

Obviously I could just leave everything in L2, and let spanning-tree block ports, but we all know that's a far from perfect solution, and we'd like to avoid the convergence time and potential hiccups that come from relying on STP.

This is where things get tricky - the 2960's have very limited L3 capabilities. They do not support dynamic routing, but do support up to 16 static routes.

With that said, what do you guys think the best way to tackle this would be?

Thanks in advance!