tl;dr - Jim Webb would be a perfect fit for Secretary of Defense. He's extremely qualified with foreign policy experience. He's a true moderate that's a Democrat in name only, and his stances are actually quite similar to Trump (just without the extremely polarizing and offensive language).

He's opposed to the Iran deal. He was one of the few people that actually came out and opposed the War in Iraq before it was declared. He very accurately predicted in August 2015 during his campaign that working midwest white voters were the key to this election, and his proposed solution was to cut the corporate tax rate, bring offshore money back into the US, and incentivize infrastructure investments to bring jobs back into the USA, specifically the midwest. AKA exactly what won Trump the election.

I doubt this will happen, but I would love to see Jim Webb be considered for Secretary of Defense or Secretary of Veterans Affairs.

He was one of the few people that opposed the Iraq War before it was ever declared.

He authored and introduced the Post 9/11 GI Bill, which is a very powerful and popular law that supports Trump's campaign narrative that we should finally start taking care of our veterans.

Although he served in the Senate as a Democrat, he was the prime example of a conservative blue dog Democrat. Yet he also served as the Secretary of the Navy under Ronald Reagan in the 80s. He is a true moderate.

He resigned as SECNAV in protest because he wanted to increase the size of the Navy, and was strongly opposed to decreasing its size. Something that Donald Trump supports.

Most people remember him for being the guy that complained about not getting enough time during the first Democratic debate, but I felt like he gave a very strong performance that was overlooked.

On a national Democratic debate stage, surrounded by far left liberals and socialists, he openly admitted to being a gun owner and NRA supporter, and called out Hillary Clinton for wanting to take away guns from ordinary citizens, while she keeps armed guards around her 24/7.

He was also the only candidate on the stage to even say a word about China, and expressed how important it is to prevent their expanding military and cybersecurity aggression. On a Democratic debate stage next to Hillary Clinton, who of course did not address the issue. Relations with China were a big part of Trump's campaign speeches.

Webb's campaign never took off because true moderate blue dogs like himself were abandoned by the Democratic party, in favor of extreme leftist liberal ideology from Clinton and Sanders. Much like Trump's supporters. So he officially left the party and said he was very uncomfortable with their views. He didn't answer yes/no to supporting Trump, but he quickly came out against Hillary Clinton shortly afterwards.

It would be a great "reach across the aisle", although I wouldn't even technically call it that, because Webb is a military leader, and not a career politician. His background is not in politics, and he does not think or speak like one. He is a boring, dry, yet super intelligent and experienced policy guru. This will never win more than 1% in the polls, but it is great for an appointed technical position like this.

He is a great person with great character. I think he would be a great fit on the Cabinet, and I really hope that this longshot comes through.

EDIT: I would highly recommend watching this 4-minute interview with Webb in August 2015.

He explicitly said that the white working class vote was the key to this election, and called out the Democratic Party for not including them in their campaign. In August 2015. He was dead on the money, but nobody cared or listened to him.

When he was asked for a solution, he proposed cutting(!) the corporate tax rate, and incentivizing infrastructure investments to create jobs here in America, specifically within poor midwest areas. He is seriously a Democrat in name only. His answers were exactly what Trump promised to America, and why he got elected. Only Webb figured it out way before everyone else. I love this guy.