With 100 feet to move, time and fuel are likely not a large issue.
"A small parcel" was mentioned by the OP.
Ok. Let's do the math and the op can judge for himself:
A rear grapple might grab two of these stem pieces, He will have to maneuver backward to position the logs to line up the rear grapple especially for a multiple log "bite" so a lot of back and forth movements. A turn will be 200' and I will discount the back and forth for positioning because he would do that anyway to load a trailer but his loading work will always be in front of him.
So he carries say only 6 logs on a trailer but that is 400' saved or more than the length of a foot ball field. If he carries 8 logs, that is two football fields saved. It adds up surprisingly fast.
How long in time is a turn?
How many logs does he have?
How large in diameter are the stem pieces?
Does the op even care about time?
Whether it'd be a small wood plot or 90 acre logging parcel, forwarding logs has it's place.
As far as logistics, he already has a front grapple. All he needs is a small trailer and he doesn't have to fabricate anything. Heck, he can even load a ground chain, wrap up the chain and skid those out.
I'll leave it up to him because no one here knows the variables.
The op might just love to tinker and make things so creating a rear grapple simply adds joy to his life.
I, being a retired logger, looks at things in time only because time was money.
My boss even frowned upon (and that's putting it mildly) his guys "blipping" a chainsaw because that wasted fuel.
Efficiency was king so right or wrong, that is the approach I bring forth.