Honestly- I would not expect that your preschool is going to change its schedule just for 1 kid. If he is tired at naptime and needs to nap then, its probably going to happen. They can't keep him up when the other kids are resting and then have him be cranky for the afternoon.
About your home schedule- is your son TIRED before 10 PM, but just doesn't want to go to sleep? Or is he really not sleepy until 10 PM? Some little kids- including my son when he was small, and still, at age 10- are just night owls!
Seriously, if there was ANYTHING going on at night, my son wanted to be around for it, whether he had napped that day or not. He stopped taking official afternoon naps very early- and he really was tired and cranky and still needed one! It just depends on the kid.
I know this might sound like weird advice- and please understand that my son has a regular bedtime and I don't advocate just letting kids stay up whenever they feel like it- but with your son's schedule being what it is, is it hurting anything to put him down at 9 or 10 PM?
1)Can he get up ok in the morning at the time he needs to be up? Is he alert and well-rested for the school day?
2) What time do you and your husband go to bed? Is it a problem if he goes to bed at 9 and you go to bed at 10 or something like that?
3)I assume you've tried all the usual 'bedtime routine' stuff- bath, special story, soft nightlight, bunny or blankie, etc.?
If he is still napping at school each day, then he still really needs that nap, despite the fact that its inconvenient for your schedule. But you and your husband need some grownup time in the evening too.
Maybe you can 'ease' him into bedtime. Set a kitchen timer for half an hour before you start your 'bedtime routine. Start out setting it later at night ( say 9:30) so he is in bed at 10. Then after a few days, set the timer starting at 9, then 8, and so on- so his bedtime prep time is always the same, you just move it a little earlier every few days. Hopefully then you can 'fool' him into actually falling asleep earlier.