What feats besides beside being known for being the strongest man with the strongest devil fruit ability?
That is a reference to his reputation. His feats would be composed of everything that happened during the war, even after being betrayed by Squardo.
What is there to support a "considerable" distance? I'm waiting.
Above.
What about Shanks seeing Mihawk as his equal, what about Mihawk leaving the war without a single scratch, what about Mihawk being feared by everyone but the highest tier characters, what about him being Zoro's final goal, what about Mihawk following Silver's steps as a partner to the Pirate King?
Shanks relationship with Mihawk is what it is, I don't see that as much of an indicator. Mihawk left the war unscathed because he didn't get involved with any of the monsters around for any considerable amount of time, Vista and later Croc are the only two people of note that he engaged, and the battle against Croc isn't shown. Mihawk's attack against Jozu and his duel with Vista that stood as a draw before being interrupted are far better indicator of his abilities, mainly because his abilities are shown; quite frankly they are the only time we've seen his abilities on display against individuals of notable power and ability. If his ability is somewhat comparable to Vista's, or marginally superior, I don't think it's a stretch to say he's a ways away from WB, very few would likely object if I laid the claim that Vista was a long way from WB in power. Being Zoro's final goal doesn't mean he was near to WB in power, and Zoro's goal is to defeat him, be better than he is. I'm not sure what the reference to Silver was about.
In fact, there are several more arguments to be made for Mihawk being an end game character like the Yonkou than him being far away from WB/Shanks/Kaidou or Big Mom.
And these arguments and their relevance to his ability compared to WB's during the war are?
Or are you trying to tell me that Shanks was far apart from Whitebeard too? Well, that would be nothing but a creation of your fantasy.
I wouldn't be able to give many specifics on how Shanks compares to WB, although I believe him to be inferior, by how much, I don't know. And I also don't know precise difference in ability between Shanks and Mihawk. What the manga did provide was a clear comparison of Mihawk's ability to a WB commander, or two of them in particular, through different means. And those are the only clear comparisons in ability that we've seen.