K.W.
I have off the chart tall kids and my son also slept in a pak in play until he was 18 mths and I thought he was too big (shamefully I look at photo's now and think he was too big about 3 to 4 mths before I took him out, bad mommy ha ha. Anyway, I have found now that there are actually larger pak and plays if you don't need all the fancy stuff at Wal-Mart.
If that is still too small, I would go the sleeping bag and pull out chair route. You can get them at Wal-Mart or Target and they are those fuzzy covered chairs, but some of them pull out like a lounger. VERY portable, can be smushed into a suitcase or even bought while at grandparents.
good luck