The other smart people in here have already touched on a lot of the things you'll want to consider. Based on your recent long efforts I have no doubt that it might hurt but that you can knock out 50 miles, so you have to look at what could keep you from finishing.
1. Bonking from lack of calories. - since you're mostly hiking and not running, hopefully you won't have the stomach issues so common in ultras. When running long the goal is to get in 250-350 calories an hour, with hiking I'd think you could get away with less. Maybe just try to be sure to get in 250 every 2 hours, something like that. But figure out the best you can beforehand what works for you in terms of eating while hiking and what you'll turn to if that stops working. For example you plan on munching on a handful of trail mix or half of a Cliff Bar once an hour, but you have some Tailwind or GU Brew powder you can mix into your water if your stomach just doesn't want any more solid food.
2. Dehydration - you're an experienced hiker, so I'm sure you've got water figured out.
3. Heat - assuming this is self supported not much you can do other than plan for what you'll do if you start overheating, which basically means get wet if there are creek crossings or water sources. In that scenario a hat and bandana around your neck that you can get wet can help. If you are going to have support crew meeting you out there, have them bring ice and load up your hydration bladder, hat, bandana, sports bra, etc.
4. Blisters - Nothing like a 1/4 inch spot on your foot ending your day. Make sure your shoes and socks are dialed in. If it's dusty or sandy, consider cleaning your feet and changing socks once or twice. If you are getting wet to deal with heat, do your best to keep your feet dry, or change socks more often. Have a foot care kit with you to deal with blisters if you get them - tape, moleskin, alcohol pad, non-petroleum based lube, a needle, etc. If you haven't dealt with blisters before,
this is a good resource.
5. Chafing - ok, this doesn't usually end an event, but it sure can make it miserable. Obviously having your gear dialed in helps, but you still may find that a pack that has never given you problems starts to do so after 10, 11, 12 hours. So I'd recommend lubing up at any possible friction points before hand, and bring some with you as well.
Squirrel's Nut Butter or
body glide are the two I've used the most.
Sounds like a blast, I'm jealous! Where are you going to do this? A lot of the above was under the assumption that you'd be out in the mountains somewhere, obviously the planning gets a whole lot easier if you're in town or if you're looping back to your house or car.
ETA - just saw your last post. Yeah, you've got this no problem then. Just keep moving, eat some food now and then, stay hydrated, and take care of any blisters or chafing before they become a problem.