I will sound radical, but here I come:
If there are any ads, in any form, I'm out of here. There are many reasons for this: No matter if they are intrusive or not, they generate traffic to url's known to trackers, so browsing MD at work becomes a no-go. It may not be a lot, but the traffic generated by the ad request and the ad itself is an aditional data transfer weight that I just don't have to handle. The script needed to load the ads and to track them is aditional load time, maybe insignificant, that I don't need (and this load time increase will be felt with each reload, I know, cache and stuff, doesn't matter). It's against my principles: I'm willing to pay for a job well done, and for a service served well; I'm not willing to accept a worse service just because I didn't pay for it. And it's bad for you guys from a legal perspective aswell: as long as you operate on a donation basis, no one can actually bring you to court over copyright issues if you heed their cease and dessist letter becuase you are not making money on someone's IP; you getting paid is not directly related to you offering someone's IP. Now if you run ads, even if you justify it as being not for profit but for self sustain, the money you make is directly related to the amount of people that have consumed a product you don't have rights over. And also, from a reader's perspective, you would just become another aggregator.
I may be misjudging the comunity by a lot. But if you only need about $1000 a month to run I don't see how a donation system would not suffice. You can set it up with Paypal, Patreon, SubscribeStar, there are a lot of middlemen that could help. And even if you opt not to go for a middleman and talk it out with your bank you could probably make something work. From a taxing perspective it may, or may not be a pain, I don't know how it works over there.