Dear Nathan,
BPTA-WDPO11DA-PWM can be installed on LianLi 011D-xl ROG certified but as you said there is a gap. About the gap, you can refer to the installation guide of BPTA-WDPO11DXLA-PWM. You can use the baffle to cover the gap.
Any question, feel free to contact us.
https://shop.bitspower.com/index.php?route=product/search&search=A-PWM