Can I intercrop during the long red sanders gestation to earn in the meantime?

Because red sanders is extremely slow growing and takes many decades for good heartwood, you cannot rely on the trees themselves for income for a very long time, so intercropping in the early years is sensible if you do plant. In the first few years while the trees are small you can grow pulses, groundnut, millets or other dryland crops between rows for cash. But be honest with yourself about the timeline. The trees may not give a real return in your own working lifetime, and felling, transport and sale are legally restricted. Treat any income from the trees as a very long term, uncertain inheritance, and make sure your actual yearly living comes from the intercrops and other farming, not from a future red sanders payout. Verify the legal felling and transit position with the forest department before you commit land to it.