unbinding hydraulic calipers - best practices

little background...got too busy pre-race and didn't check my disc brake pads. Sure enough, 19 miles into a 41 mile race and those pads are worn to nothing. Worse, yet, the caliper was clinched on the wheel, making the brake slightly engaged for the next 20+ miles. Hardest ride ever!

Anyway, back to the matter at hand...

When I got home (after a few days of recovery) I went to put in new pads and I've read that one can push back on the inside of the caliper body to ease the actuator back out. So I slowly tried to ease them back out. I put the new pads in and I wedged the red plastic thingy that comes with the disc brake pads and hammered on it gently to open up space. That wasn't quite enough so then I inserted the old pad body in there and did the same. I even sanded the new pads slightly to shave off a few mils. I wrestled with it quite a bit and it seemed pretty stubborn.

When all was said and done, the pads are not binding like they were but I still haven't been quite able to open it enough to get totally free movement from the wheel. If I give it a good spin by hand, it will come to stop within 3 rotations. So I can coast on the flats now, but there's definitely some slight resistance that can be felt.

Basically, does anybody have any best practices they wanna share for re-opening the space in a hydraulic disc caliper? The bike is definitely 1000x more rideable than on race day but I'd like to get that last bit of drag out.

It's worth mentioning also that these pads are not OEM. They're cheap metallic pads I found with reasonable amazon reviews. I only mention this incase thickness is infact an issue. (or something else I'm overlooking)

these are TRP Hylex brakes, if it matters

thx