IMO, I agree FD did not plan on the quantity of blood and extensive cleanup needed. Odd though that he grabbed JFd's cellphone, which was likely inside JFd's purse, so if the plan made in advance was to fake an abduction, why grab the cellphone and leave the purse behind?
I know young people and some men tend to carry their cellphones in their pants pockets, but I and most mothers I know - and certainly those of us in our 50's or 60's, keep our cellphones in our purses. I don't know what JFd's habits about this were.
IMO, there was quite a lot of panic at 69 Welles Ln about the quantity of blood after the attack, so plans went awry, time was ticking, and the attacker(s) were behaving in a disorganized way, but I strongly believe the Suburban left as it was (running lights on and transmission in "Reverse") and where it was (outside the park, rather than at a parking lot in the park) was reflective of that panic rather than as part of an original plan to fake an abduction which was supposed to have occurred at the site of the Suburban. At best, it was a poorly improvised alternative to the original plan.
If using a faked abduction to draw attention away from himself as most likely person-of-interest, IMO FD and his associate(s) would have developed plans to: transfer body, bags, and Suburban's cargo area mat to Tacoma, then park the Suburban in a parking lot at the park, then lock the doors, and then toss the keys (and possibly the phone, with SIM card removed) into some brush - to leave the impression that JFd had gone for a quick morning walk or run in the park and was abducted or attacked by a serial rapist and dragged off to some hidden location there -, and then ride bicycle from parked Suburban back to the Tacoma.
Perhaps that WAS the plan, but IMO the long clean up at the attack scene had eaten up all the time before an alarm might be expected to arise about JFd missing and not returning calls, so FD - in increasing panic about the potential for being caught with her body in close proximity to JFd's home - had to improvise and made multiple mistakes: forgot to grab the purse even while grabbing the cellphone out of it (that purse left at home with cellphone missing would be a big red flag, IMO), left the Suburban outside the park - close to where the Tacoma had been parked for over two hours - rather than in a parking lot inside the park away from where the Tacoma had been, moved the Suburban just a short distance away from Tacoma and forget to put transmission in "Park" in his hurry to get away, and left blood on the outside of the Suburban as well as inside the cargo area of the Suburban (even though the cargo mat was removed).
So, all that said, I think there may have been an original "make it look like an abduction at the park" plan, but a long and unplanned cleanup of blood at the attack scene necessitated new plans be improvised to make up for lost time. Once back on track with the original plan, FD went on his merry way as though the original plan had been followed without considering the many ways his disorganization at the first and second scene would point investigators back at him abducting JFd from her house rather than at a stranger-abductor taking JFd after she pulled over to the side of the road.