Well, you could roll your own DC voltage boost circuit, but they are also inherently noise since they involve switching regulator circuits. Then you would have to hack the charger to operate from the switching regulator DC output. All in all a lot of work just to avoid doing something that subjectively "just seems wrong". In engineering sometimes it's better to go with the simplest solution and not the most elegant.
Using an inverter may not be the neatest solution, but it's the easiest and should work. Unless you are very concerned about efficiency, that should be tolerable also. Bringing the AC voltage back down to 24V usually involves a transformer in the charger, which is quite efficient. Use an inverter not much larger than you need and check its no load current, which will give you an idea of its efficiency (the charger likely doesn't take much power so you should be able to use a small inverter).