If you are wanting something removable, Why mount it? Look at a no-drill option. Something like this:
https://www.discountramps.com/black-...YaAm2TEALw_wcB
A couple ratchet straps to hold it in place, a couple to hold the bike from backing up out of the chock and hold it in place and you should be good to go. Tie Downs have ratings all over the place depending on the manufacture. I don't remember what the ones in my Wolfpack are but it was significantly more than I was ever going to put on them with a 1000 lb golf cart as long as I used multiple straps, which I do.
That said, If you want to bolt through the floor, The coroplast you're seeing underneath can be dropped by removing the self tapping screws in it that are screwed into the frame and cross members. May still have to dig through some insulation or other situations to get a backer plate and use a bolt through process but I'm sure someone has done it.