Minn-Kota MK330D or NOCO Genius GEN3 30 Amp ..... but, in your case I'd say the NOCO (based on size) but even that may be too big The dimensions of the NOCO are :15.67lbs | 13.66 × 10.94 × 5.87The dimensions of the MK330D are : 20lbs - 16.25 in x 7.5 in x 4 in
You can also mount these other than laying flat, so your 12x8 space may still work ??