I agree with each person needing to decide whats best but if you're in a sunny spot I'd give solar a tad more credit than you are. 50ah over 3 days is ~17ah a day. Assuming you can get 5hrs of good sun and your using a basic PWM controller 17ah/5hrs*14V= 47.6w of adjusted solar, 47.6*18V/14V= ~60watts of panel most likely needed. That is smack in the 30-100w range you were blowing off. You can pick up an 80w panel and a Morningstar Sunsaver SS-6 for ~$200. That isn't quite as our of reach as you might think and if you're only using ~17ah a day that will extend your 3-4days much more than 5 even in less than ideal light. 80w/18V=4.45amps (not I didn't account for MPPT here, this would be PWM numbers), 4.45amps per hour of good light. Only got 2hrs of good light? Well now you're only having ~8ah deficit a day, you've just doubled your stay. A little over 4hrs and you're coming up even.
But yes only around 30W doesn't do much unless you're a much lower ah user, which someone without a fridge might be (the OP didn't say anything about a fridge so I was just showing him a cheaper source for a panel/controller in the range he was looking at).