RE: Need help saying Thanks...
GregH gives good advice, Aaron. You need to convey to him EXACTLY how much it means to you.....that he has entrusted you with being a good steward of his property.
The only thing I'd disagree with Greg on (through my own personal experiences with the properties I hunt).....is...I'm not so sure a photo is in order....especially of a dead deer. MOST (as I'm thinking about.....all but 1) of my landowners are borderline animal LOVERS. I don't ever take a deer out of my wood sin the daylight where the deer is visible to anyone. If it's night....I just carry it on the 4-wheeler. If it's daylight......I check to see if anyone's around.....and if they are....I take a trailer and a tarp and cover the animal up. I'd rather be safe than sorry. A photo of yourself (no camo) is a great idea, though.
Every time I've ever asked for hunting permission....I've sent the landwoner a hand-written note. It's gotten me into my best two spots....when initially I was told "no". On both occasions.....the landowner received my letter (mailed) and changed their mind.
If it were me.....you already HAVE permission. I'd send the FIRST letter simply thanking him for entrusting you with his land. I'd send the photo here. Secondly.....I'd send a follow-up letter a few weeks later......and mention the clean-up, then.
The best advice I could give you is to word it like you're "in"....and never leave room for anything else. The fact that you're "there" is an afterthought. You just want to show your appreciation.
Good luck.