I think the key is to work with your lo and hopefully CIO won't be an option (for me is isn't even under those circumstances) - in fact Tracy suggests if it gets to that to sit in a dark wardrobe with your lo to help drown out the outside world until your lo falls asleep. CIO in the arms of someone they love is OK, just not alone.
As far as overstimulation, yes definitely have a good 20mins of quiet, calm, dimmed room, gentle story reading, cuddling before you think your lo is likely to get tired. At first yawn lay him down quietly into bed and start patting. If you do think overstimulation is a problem, what I'd do is have a few days where you're at home, keep EVERYTHING low key at all times, observe closely and follow cues. Once you see what's happening, then you will probably find it a bit easier to add more stimulating activity back in.
How old is your lo? Do you think his 45min naps could be related to too short activity time and maybe he wants to be up longer? At some point too short an activity will mean short naps. OK, just noticed he's just past 3mths - are you in the process of changing his routine perhaps? Maybe looking at switching to the 4hr EASY?
FWIW, my dd has only ever done 45min naps in the morning, I've figured this is just her natural rhythm - my rule is, if she was happy I got her up, if she was grumpy I'd resettle her for a longer nap. She makes up for it by having a long afternoon nap.