I am currently having a similar issue. I found that changing "mods" folder to "_mods" allows LSPDFR to launch (I've done a complete clean reset install). This solves the launch problem but prevents me from adding cars.
Try that, and then maybe together we can find a solution to the problem. But if it's a clean install it sounds like the same problem I'm currently having.
The mods folder is crashing LSPDFR. Clean install of everything, no mods yet other than LSPDFR. No cars. No ELS. Ive removed everything suggested, verified game files. Everything imaginable to me. The only thing that fixes LSPDFR's crashing is changing mods to _mods. Please help.