Are you able to try WILDing during a morning/afternoon nap? It's basically an extended WBTB. Wake up a couple hours earlier than you normally would. Then just do whatever for 2-3 hours. Then take a nap and try to WILD. As long as you keep the nap within 4 hours from waking up, you'll still be at a point where you are able to enter long REM periods pretty much right away. After 4 hours...such as a nap in the evening...it becomes much harder to have an LD because your naps will be mostly non/shorter-REM later in the day.

Since you seem to be having difficulties finding the sweet spot, you might have some success if you try the morning nap, which is sort of like a plain WILD combined with a WBTB/WILD. Make sure you give yourself plenty of time to nap...at least 45 min - 1.5 hr or longer.