My LO is 10 weeks old and fights naps all day long, I also have a 21mo. old son at home too. He struggles so much getting past that 1st 20 min. into a deep sleep. I cannot sit in the nursery in the dark and rock him to sleep for naps when I have a toddler running around. I tried baby wearing using the Moby and the Ergo without success. How do you do it if your newborn is difficult? He hates the swing too. If you do baby wear for naps do you wear them the whole time or lay them down when they are in a deep sleep?
Re: Fighting naps
I agree with pp about walking the dog while wearing the infant for a nap. For me, DD2 would fall asleep or be nice and relaxed while I wore her facing me and I'd be able to transfer her to her tummy in her crib (I know, I know, but it was only for a nap and we take all the other SIDS precautions). I'd also sometimes set DD1 in front of the TV so I could nurse DD2 to sleep laying in the middle of my bed. You do what you have to do. Sleep is too important for everyone to be missing out! : (
Also, not CIO but are you letting him fuss at all at the 20 minute mark? Both of mine would let out a good wail once or twice (especially if overtired!!) and then settle down and get to sleep. I'd give him 5 minutes or so to try to figure it out before assuming that the nap is over.