Recently acquired a Perun moto rack and it’s brilliant. Done 5500 km tour in ever condition and am very happy. 
just toying with the idea of sticking a small pelicase on it because i can, but wondering whether anybody has done it and got some pointers / pictures perhaps? TIA

A good plan. Peli cases are one item that earns its reputation. I have some adapters to put on them (or any case) to go on side cases, but there will be quick detachable adapters for top racks too. 
waterproof , robust and lockable. What’s not to like? 👍

Welcome to the club!

 

https://www.tenere700.net/topic/4868-perun-moto-rear-rack/#comment-56312