Seriously, dedicate a portion of the land towards geothermal power. Any good cook, and any good engineer will tell you that when you want to keep heat under control, you reroute it elsewhere. Build some geothermal plants on the spot, you know how deep the magma is, then building vent/transfer systems around the caldera will in fact cool it down to prevent an eruption, AND you can sell the electricity generated for, well, generations.
Sheiss, it's so simple, should I really be the one suggesting this? I'm a high school dropout (intellectual as I am), and it's really that obvious.