Dehumidifier Recommendations please?

pick out based on volume of your tent... tents are a small volume, so you don't need a duhum big enough for alarge room -- unless you want to control the whole room - e.g. maybe, it contains more than 1 tent. you can very likely buy the smallest one you can find and it'll work fine. Options for drainage might be a better factor to key in on. something with a tube you can run out to the drain as opposed to a bucket to empty everyday.

10-20% is way too low, you should be around 60% for veg and between 40-50% for flower. Because you are running an exhaust fan the best bet is to put a decent sized dehumidifier outstide the tent near your intake. A decent dehumidifier will run you a couple hundred, but its better than bud rot. Happy growing.