Where'd Our Good Sleeper Run Off To?!

We've been blessed with such an easy going little boy!  He's always been a happy boy only getting upset when he was hurt or sick and maybe a little bit when tired.  Lately, it has been a whole different story!  I don't know where our good sleep has run off to, and who this not so good sleeper might be. 

Luckily, he's still taking good naps, but sometimes I wonder if he's too good at napping.  His bedtimes have been so drawn out lately (consistently for 2+ weeks), that we've even asked my mom to limit his nap and wake him up at 4 p.m... I know, I know "never wake a sleeping baby" but he simply isn't sleeping like he has in the past and I'm not really sure where else to go with making bedtime easier.

I think he needs to be going to bed around 8:30-9 p.m. (which is probably later than most kids his age), especially if he's sleeping during his afternoon nap until 4 p.m.  Not to mention with all of this rain, we can't seem to get him outside to burn off all of his energy.  We've tried a few different things with a bedtime routine... we haven't done a bath every night before bed because a) his skin gets so dried out from baths and b) with Matt often working until 8, trying to give a 2 year old a bath while pregnant is not an easy feat... I just don't necessarily feel that safe doing it.  Heaven forbid we both slip and fall because of me trying to get him out of a bath with wet floors. 

We need to figure out something soon because we want to switch him into his big boy bed (soon after the bunk beds arrive) and the scientist in me thinks it would be best to only change one variable at a time.  Anyone have a similar experience with toddler sleep regression?  Any suggestions on bedtime routines or other things we can try to get him to wind down in advance of bedtime?