My bf moved with me to the LA area from Illinois last year (he was in Chicago, I was 3 hrs away); my research advisor moved universities and he was able to internally transfer in his job, which was *awesome*. We were together almost 3 years at that point, now at 4.5. Our situation was similar to yours in terms of distribution but total was like half yours.
We set out expectations as follows:
->As the lower earner I set my upper limit on rent, and we would split equally. We didn't really discuss this at length, but if he had wanted a pricier apartment, I was ready to suggest he cover the difference from half my proposed amount to the higher cost. (My limit was $1500. We ended up finding an awesome place for $1250 largely by getting lucky.)
->We would split all other normal living expenses equally (groceries/tp/cleaning, internet, electric, etc)
-> He actually proposed that he would cover the cost of buying a car, but we would split operating expenses (gas, insurance). He drove to work but was generous with making it available to me as needed (when I have doctor appt or similar mid-day, need to take something heavy/bulky to work, etc). We also worked together on picking it out (he wanted to make sure I was comfortable driving it <3)
-> We would buy our own "stuff" or any extras that the other does not agree upon (e.g. if he wanted to get cable, which he doesn't, or when he wanted to get an Amazon Echo, which he actually did) and not have more than "mild disapproval" power over each other's choices. We aren't married yet, after all.
How it actually worked out: personal items sometimes end up in a Target run and it seems stupid to check out separately. We also buy household stuff jointly (we needed a lamp, chairs, a few rugs, etc that we didn't have in IL because our roommates did).
I gave you that summary to show (a) how another couple (quite functional, I'd like to think!) handles the situation, and (b) where my biases might lie, so you could take my suggestions with a grain of salt.
I think you should figure out what your alternate housing would look like if you didn't move in with him (Shared apt with roommate, rent+utilities? Studio apt in a cheaper neighborhood? Whatever you're doing now?). Offer him that as rent in his house. I wouldn't include the costs of a longer commute in that calculation; it's hard to account for how much time and money you'd spend commuting to see him if you lived separately. If he thinks your suggestion is unreasonable, I have to agree with more4less:
Your boyfriend is a schmuck. And you should be happy that you found it early enough.
You aren't married or even engaged yet so I don't think it's right for the lower earner (i.e. you) to suggest to split expenses by income %; it would be different if he proposed it, but it may feel to him like you're trying to take advantage of his income/live off him. BUT like you said, you shouldn't be responsible for his decision to buy a house; if he wants "extras" over the standard of living YOU can afford, I think it's his responsibility to (a) do/buy these things without your participation or (b) subsidize your participation by paying anything over what you CAN afford (or are willing, or have in your budget), if he wants you to partake.
I do think things change when you get married, as you become one legal entity and have invested in each other by entering that contract and thus some form of pooling finances makes sense (whether that's actual 100% joint pool, perhaps less "fun money" or similar, or responsibility for different bills/expenses, or percentage-based splits). But as bf/gf you're independent entities even if you household together, and it's responsible to treat your finances as such.