Im sad to be late to this one!
Firstly I’ll refer you to this thread which will very likely make your day:
Same thing on a Toro
Next, i’ll say that it’s a less scary thought than you might assume durability wise, because a front mount mower is basicaly built like a backwards tractor. Thats good in the sense that unlike a ‘regular’ tractor the loader weight is mostly carried by the stronger axle and not the weaker one! I personally wouldnt be too concerned about axle durability. The downside is that unlike a ‘regular’ tractor you cant easily add the required counterweight by hanging something on the 3pt hitch, because you dont have one.
I think the idea of a loader on that type of machine is tenable but will take a lot of effort to be ‘as good’ as a garden tractor with a loader (comparable size class) mostly because it’ll require a more complicated design both in terms of mounting the loader, and in terms of adding the required counterweight without ruining the steering effort.
I would be excited if you decided to take it on. The result would be a pretty cool machine as long as it could lift at least 3-400lb and not be a pita/deathtrap to operate. I once mounted a 500lb crane to the front of a converted riding mower and that presented all kinds of issues which i mostly worked out and ended up with a cool little machine that i was glad i built. I havent touched it in a long time but im still so affectionate towards that project that i keep it around for an eventual ‘round 2’. So i doubt you’ll regret it either way.