Well, the main point of this match is patience and precision. You basically have to be a surgeon here and only take what you know you have...
you have to realize that if you get too ambitious with a dair, usmash, or even a grab, you can be punished hardcore for it.
Snakes LOVE to turtle in their shield after forcing you to approach. you attack, they spot dodge tilt you. The difference in this match is that you don't really need to approach, unless it's clearly open. You have to do a LOT of waiting for dodges here, otherwise you take punishment.
Now all that is not to say that it's a bad match. it's certainly not. Fox is one of the best against Snake...you just have to be really careful. Personally, I believe this match is a true testament to your mindgaming ability. If you are a noob Fox, you will get hit by every tilt he throws by being predictable...so you HAVE to grow in your game and learn to be smart.
As for general strategy:
Lasers are your best friend...I'm not saying just stand there and fire away...use SHs and such...but racking that damage without real fear of punishment is nice. He will (usually) approach with mortar slide, which you can dair him out of. At that point, he's yours. dair, utilt x3, grab throw continue works...just when it's done...when he can defend himself...do NOT try to continue it. go back to lasers. If he's above 90%...that's usmash kill range...don't just go nuts and throw them all over the place...really plan it out. REALLY be careful about it. I would almost recommend disregarding your usmash unless it's just obvious...and going for a bair kill instead. Dair usmash will combo late in the % game...so watch for that.
Grabs are your second best friend. if you really want to approach Snake, a pivot wave grab is probably your safest bet as, if he dodges it, you slide out of scary range. In this match, probably up and down are your best throws. In the air, you can bait Snake out and punish him...you straight up can beat him in the air, so putting him in that position is a good idea.
Play around with shine dairs...don't just go for a dair...his utilt beats it. do a shine or two...or three, then dair his whiff. that's your best option. again, don't just be predictable about it, or he will jump and uair you out of it. mix things up.
Often in this match, it's best to just avoid confrontation. Instead of coming down with a dair, DI to the side, and just get away. start it over...even footing. It's really easy to slip into aggressiveness, and get your stock taken away just like that.
Edgeguarding...your best area here.
First of all...Snake's recovery is really easy to read. that's an overall Snake weakness in this game. USE IT AGAINST HIM.
Special things to note here. Strong Nair (hit at the beginning of the nair), uair, and bair all hit him out of his upB. The bair is underlined because it kills pretty early....so keep it in mind.
Yes, you can grab his recovery if the player is stupid enough to upB by the stage (you then DON'T attack or throw him, and he tumbles down, without a jump), but then, he just C4's his way back onto the stage...it's a great way to put dammage on him, but usually won't work to kill him. One thing I like doing is intentionally missing that grab, then edgehogging VERY quickly...often, this will surprise him into death. otherwise, a stage spiking bair is always good...and if nothing else, sure, land the grab.
When you hit him out, the Snake will usually recover high enough so you can't aerial him out of his upB (may start doing this after you catch it once). From this point, he's coming down onto the stage, where you are. If you stay on the ground (as you should) he has basically two options, if you play it correctly:
1. attack you with an aerial
2. airdodge into the ground
realize that both of these are punishable...even with an usmash out of shield... there's your killing opportunity, if you're fast enough. just be fast.
almost everytime he's in the air, and you're on the ground, he will do one of those two things. this is why I say you have to be a surgeon. He WILL give you chances, you just have to be really patient and wait for them.
That's also why I say throwing him into the air is a good idea...
basically, I say the match is straight up 5-5 even. I can see how it would be anywhere from 4-6 to 6-4 for each of the characters... but it's certainly winnable...
Some Foxes will come in here saying the match is impossible....it's not...it just requires a different Fox style and a LOT of patience and precision. certainly not that bad of a match for Fox.