I agree with Andi, my BOE guide did bend over backward to make sure my vegan diet was accommodated. If the guide is not familiar with Paleo, I would probably emphasize no dairy (and just guessing this is most important, but you pick the biggest problem food group for you) and work your way from there.
In thinking about what others were eating for their group meals it seemed pretty meaty from a vegan perspective, lol, so I think you will be fine. In nearly every situation the group meals were 3 courses, starter/entree/dessert so a gracious plenty as far as food is concerned. I almost always wound up being offered fruit for dessert, sometimes just cut fresh fruit, sometimes slightly sugared. The first night is a rijkstaffel in Haarlem which included many meat dishes to be eaten over rice. The rice is in separate bowls, so no problem avoiding that.
I would put some thought in to breakfast. It seemed like most places had a boiler thing for people to do soft or hard cooked eggs, and usually had some kind of fresh fruit. Most places had cold cuts and cheese as well both of which I imagine you avoid and of course croissants, bread and sometimes cake.
I do not believe legumes were served to the group at all. I had them in Cinque Terre at the group meal but IIRC that was the only time and that was my vegan plate, no one else got them.
There was a lot of alcohol in the form of wine, but no problem for you to avoid that. There were several people who did not choose alcohol on my trip and there was absolutely no issue. I do not believe there was ever a time food was cooked in alcohol. Well, except for a meat dish in Florence, but he flamed it tableside so the alcohol would have burned off.
I also started out telling my guide that I would be happy to figure out my own meals if he could tell me which group meals would be unlikely or unable to work with a vegan selection. He assured me this was not a problem, and he was 100% correct. I always had back up food just in case but never needed it.
By the way, when there is a gelato stop in Italy, you might try the sorbets. They do not have dairy altho there is some sugar. The fresh fruit ones were outstanding. I was there in the Fall and in various places had peach, pear and green apple. Oh. my. word.
Have a wonderful time! I so loved the BOE tour and I literally think about it every single day.