Onboarding for high-volume crypto payments – friction points and PSP selection

We're scaling up our operations to handle significantly larger crypto payment volumes, particularly focusing on $USDT and $BTC settlements. Our current PSP, while adequate for smaller transactions, is starting to show its limits in terms of liquidity access for larger blocks and the fee structure becomes less competitive at this scale. The onboarding process with some of the larger, more institutional-grade PSPs has been surprisingly arduous, specifically around proving source of funds and ultimate beneficial ownership for several layers of corporate structure. I'm curious what others' experiences have been in navigating this, especially for entities operating cross-border.

Beyond just the KYC/AML hurdles, what specific infrastructure-related questions should we be pressing PSPs on when we're talking about high-frequency, high-value crypto payments? Things like real-time liquidity provisioning, guaranteed settlement times for larger amounts, and how their underlying cold storage/hot wallet management impacts our own operational security and audit trails. Any insights into common pitfalls or overlooked aspects would be greatly appreciated.