Identify a rigid fork with the same dimensions, same steerer tube length, and same crown race installed. Swap forks when you want suspensionless or suspension. Transfer the caliper mount/caliper over and use the squeeze-then-tighten centering method. The whole switchover could be done in a few minutes each time. It's the cleanest, cheapest, most reliable means to achieve what you want/need. Why overcomplicate it?