Ah... the muddle... and ever changing! I always capped the 2nd nap to preserver an 8pm BT... now the only time we do a second nap is if W wakes from first nap before 1:30 BUT... that is now changing as well since he is not going down now till 12:45ish (from WU at 7am) EBT is a no-no here... W won't have it at all! So, if for some reason he needs a little boost in the pm... I put him the car and drive about 5mph on our gravel road and let him sleep for 5-10 minutes...but the trick is waiting long enough after his first nap to be sure you're not driving for an hour just to get him to fall asleep for 10 minutes! AND not doing it too late that BT doesn't happen.
I agree with someone who said that a set nap time and set BT seems to work pretty well although... again, for us that is changing. I can't run errands in the morning (and hour from anything close!) and I've found that he just goes right back to sleep so I run errands when I can leave about 10:30 - know he'll sleep about 40 min in the car and then I end my errands (whether I'm done or not!) about 3:5 hours later knowing that he'll sleep again in the car...
oh the joys...one day (too soon) he'll be calling me from college at midnight with girlfriend woes

So, trying to take all this in stride! I do agree that keeping them occupied is tough for such a long time! For what it's worth... we do some workout time (he is in the playpen then) take care of our chickens and dogs, work out in the garden, I sit in the passenger seat of the car and read while he sits in the drivers seat loving the steering wheel!, we have blanket time where he plays on the floor, walker time, high chair time with a book or toy while I'm cooking, playtime with mommy and daddy in the evening, time out on the deck, piano time... I practice he bangs with me, I take him for a 4 wheeler ride about every other day and we try to find a neighbor on our gravel road who is home to visit, he loves to sit outside with me on the trampoline. He'll be walking very soon, so not expecting some of these to last very long!
Godspeed!