Simbrief will generate a reasonable cruising altitude, at least if you use a proper profile for your airplane. Not sure if they have one for the TBM 930 and Grand Caravan.
edit: They have one for the Grand Caravan (listed as “C208 - Cessna 208B”), but none for the TBM 930, only for the TBM 900. Not sure if they are close enough performance-wise. You may be able to find an unofficial profile, though.