Guilty and looking for coping methods

Come on SupernannyA. Think of your name. It's the same as changing a smaller child. My grandson only has a nighttime nappy just in case of accidents and hes only a bit younger than yours. Just brace yourself. You must have changed him when he was younger? Grin and bear it and just think of him as your lovely little grandson who through no fault of his own needs a bit of extra help. Don't think of your own offspring who were unusually early in their potty training achievements. Just try it and you might surprise yourself and the little boy will have a special time with his Supernanny!

Would it help if you wore latex disposable gloves when you change him or is it more than just touching the soiled nappy that upsets you?

As rosesarered says, it's a non-starter isn't it as clearly if you're unprepared to change his nappies then there's no way he's going to stay with you.
Apart from paying for a carer to stay at the same time (which would be pretty expensive and ludicrous imo) then that's it, sadly.

My 3 year old grandson uses a nappy overnight. My 18 month old granddaughter uses one all the time. We cope. I think you will cope with your much loved 4yr old, surely ? Just do it. You will miss so much if you don't try to get over your distaste of bodily fluids. We all have them. It's nature.

If you 'don't do bodily fluids' then you can't have him to stay, which is very sad.I had to change my disabled Grandson's nappies until he was nearly eight years old.If you love the child and want them to be happy with you, then just do it.