Read some notes on the web about towing with tractors.
Apparently it is important where you hitch the load. It must be hitched below the axle, for example to the middle drawbar. Hitching the load high is supposed to cause the tractor to do very dangerous wheelies.
The tow behind Arch would have the benefit of picking up the end of the log to reduce friction, and still could be towed behind the tractor attaching at a safe place for pulling.
It won't necessarily keep you from rolling sideways, although it might provide a little buffer between the log and the tractor.
Lets not be so tentative about this ?
NEVER tow from the 3 pt and especially not the top link attachment point.
From the ROPS - again, NEVER.
The very low gearing and incredible grip that that tractors have just about ENSURE that they will flip over backwards if you attempt to tow a load that provides enough resistance above the rear axle center.
The correct term for this is that the tractor "rotates about its rear axle".
To the O/P;
The log arch is primarily to prevent the end of your logs from digging into the ground if/when you go into a dip and then climb out.
You want to carry anything/everything as low as possible for stability, but if the butt end of a tree is being carried on the 3 pt and is too close to the ground it can dig in when at the bottom of a dip in the trail. It is then POSSIBLE for it to pivot up and over you - depends on the size of the tree, e.g. a 140 ft pine won't flip over the top of a little 25 HP yard tractor (-:
I have some general concerns about you being new to tractors and wanting to skid logs as a first or early project.
DO READ UP generally on logging with tractors, snaking tree lengths through the woods is kinda tricky to put it mildly.
Down grades can kill you if the tree starts to push the tractor. If you have any serious down grades you would be better off with a Farmi winch (or similar). You can DROP that as an emergency brake if you have to, wheeled log arches just keep on coming at you.
Farmi used to have a lot of good general forestry tips on their web site, not "training" per se, but informative.
You would be MUCH better off with a Farmi winch ANYWAY !
Dragging is orders of magnitude more risky than winching.
Not cheap, but injuries are SO much MORE expen$ive.