As for infrastructure and first line support, lobbying management for more people continuously is just about the only long term solution.
The other thing is planning and transparency which helps the above. Keep plan with realistic estimates to show it management each time you talk with them. Do your best work, definitely dont slack etc, but dont skip corners to make something look like done when it is not. Instead, move dates in plan and send it to management again. The point is to convince them that there is really more overall work then possible by one person. (If they get offended over that or treat you badly over that, find a new job.)