***Opinion coming from an insurance agent***
I would not reduce the liability coverage you currently have, in fact, higher limits (250/500 or 500/500) probably wouldn't cost you much to increase. But, I'm comfortable with 100/300, and we won't write any less than that. The risk is too great if you happen to be at fault in a large loss.
$1k deductibles are fine, if you can afford the loss. If there isn't a loan on the vehicle, you are not required to carry full coverage. So, that one is up to you.
Med payments is low, but eh, that isn't a huge player.
I like rental coverage, 30/900 is typical and is typically the lowest limits companies offer. It doesn't get you much, but it gets you wheels in case your car is down from a loss.
You are probably getting a multi-car discount for having two vehicles on the policy, as well as approximately 5% discount (varies by company) for the multi-policy discount.