I've given more glider "baths" than I can count for medical reasons, Melonleaf is correct and gave some pretty good advice.
I would NOT suggest a ecollar because of the location of his wound. Any wounds around the neck area do not use a cone/ecollar.
Before you do a bath trim the nails! I don't care how docile they are you want to trim the nails first. Wear a tank top or short sleeve shirt do NOT give him added traction especially if your doing this by yourself. I realize at 13 he's probably pretty mellow and slower than younger gliders but water may wake him up a bit
You don't want the water to warm or to cold, test it on your wrist as you would a baby bottle. You want it close to your own body temperature. Just a dab of dawn original dish soap a little goes a long way. You want to make sure you rinse really well.
Have everything you need easy to reach.
You want to give the bath with running water, do NOT fill the sink! allow it to drain but make sure to prevent the glider access to the drain.
Once the water is at the right temp hold the glider at an angle like this / with the gliders head away from the water and let the water run from the back of the head down.
Let the glider hold on to you and YOU support the glider instead of you holding the glider... Let his/her back feet hold on to your left hand as you support his upper body with your right or vice versa if your left handed, this makes them feel more stable. This will also help you keep him slanted and have more control because your not trying to control his feet.
Once wet remove him from the running water but leave it running, dab a drop of dawn on him and lather him up from the neck down don't rub right on the wound but don't worry if the soap gets on the wound it won't hurt him.
To free up your dominant hand to lather him up let him hold onto the faucet with his front feet while still supporting his back feet with your other hand he will keep his own head out of the water this way and it'll be easier to return your dominant hand and unfoot him from the facet to rinse. Just simply put your finger under his front feet and lift his feet off and let him hang on again.
Rinse well!! put him back under the water at angle as you did the first time. Now he knowssssss whats happening and may not be so mellow.
I found pajama bottoms the easiest way to dry them... I know it sounds weird
but old worn pajama's are very absorbent and you have a tunnel you can tie off the bottom of the pant leg or tuck it in the other pant leg for a bigger tunnel loop. When the glider moves through the tunnel they are going onto/into dry fabric that wicks away the wetness from the glider. This method also keeps them completely covered and safe from any cool drafts. As he tunnels cup your hand over him using dry patches of material to gently rub him dry.
I don't like using towels because the material is looped and it takes foreverrrrr to dry them. Tshirts or pajama bottoms are def easier and dry faster more thoroughly because they wick moisture away.
You do want to make sure he is dry all the way to the skin they have very dense fur. Once dry keep him on your for a while n let him absorb some of your body heat. Even if he's not a bra baby he might turn into one I've had a couple that would never stay in my bra but totally changed after having baths. I'm NOT saying to use baths for bra training, it was just a pleasant side affect of necessary medical bathing.
I've tried a ton of different methods of washing and drying.. this is what I've found is the easiest and I hope it helps you both and I hope he gets better soon.
Melonleaf, "Alright to begin with you said that you have tried using a wash cloth and baby wipes but they didn't work to get the smell out of his fur, correct? That seems a tad strange to me"
It's not strange at all. Wash clothes and baby wipes only touch the surface of very dense fur, and baby wipes even unscented ones taste HORRIBLE and will usually prevent the glider from self grooming and other gliders from grooming him because of the taste and the way they groom . They lick their toes to comb themselves so every time they lick their toe nails they taste buttwipes. It doesn't take long for them to stop grooming because of the gross taste. Which also applies to wounds draining as well I can't imagine how that tastes.
'Bathing" cleans under the dense fur all the way to the skin removing built up body oils and medical smells the glider isn't or can't take care of itself.