Both have their place, and a wise person would carry both. Depending of the type of Bowie knife, you'd more than likely have cut the sapling and be long gone using the bowie in a third of the time the multi-tool is going to take.
The Bowie will also take a lot more abuse than the multi-tool ever will. But they each have their respective uses and proper applications.
A multitool's saw -- even the Victorinox, which has the best wood saw -- is inefficient at best. The multitool has a lot of good applications, that it's a must-have, but it can't replace a good heavy-use blade.
It probably good to define the roles that each tool intends to fit, since over compromise can render good ideas impotent.
For a small tool, it's important to choose between versatility (multitool) and efficacy as a weapon (fixed or folding knife than can be concealed, rapidly deployed and has useful blade geometry). If your small tool is your primary, I think many of us would hedge our bets towards the fixed/folding knife unless we plan to work.
If the smaller tool becomes a secondary, I think it changes the dynamics towards versatility with regards to the smaller tool. For a primary blade however, I think it's hard to beat the machete as countless conflicts worldwide have shown its versatility as an edged tool and how fearsome it can be as a weapon for very little cost.
being able to adjust it would be important, esp with something readily available.
"full size" folding knives seem to have been doing very well. If the overall weight were kept low (e.g. skeletonization, use of Al/Ti on select parts) and the primary blade were easy to deploy it would help make the tool much more practical.