I have a very cool character, a wood elf. He hunts on his horse with his bow, Faendal is his best friend.
I have the mod WARZONES installed, and it's so cool, because when I'm riding on my horse and I see the imperial legion fighting bandits, I always join the imperials.
But, my question: Is it logical if a wood elf becomes an imperial soldier?

visit Imperial camps, most of the generals are non-human

That's like asking if its logical for an Australian to do anything other than ride kangaroos

While Valenwood is part of the Aldmeri Dominion, not all Bosmer live in Valenwood (such as your character, who lives in Syrim) or support the Dominion. A Bosmer could support any side he or she wanted - the Empire, the Dominion or the Stormcloaks.

Glad to heart you're enjoying your playthrough! I love hunting in Skyrim - I often fire up my Nord hunter's game for a hunt through Falkreath, the Rift or Whiterun hold.

Thanks.
At the moment I'm in the Whiterun hold, and I enjoy it really much. I like hunting on mammoths alot, and there was a group of Imperial soldiers hunting on one, so I helped them. I love the WARZONES mod, really, i recommend it.

There's even an Altmer commander in the Legion.

Why wouldn't you help the Empire? Unless they intend to stay in Skyrim permanently, most Bosmer have no reason to fight for its independence. You could side with the Aldmeri Dominion and help them crush the rebellion, or you could just believe that a united empire is better than independent provinces. It's up to you to decide.