We had a similar problem with my daughter in February. She’s almost 3 but still in a crib and she’s tall so a pack and play is extremely uncomfortable for her. We put her in a big girl bed on the trip. We hyped it up as a special part of getting to travel because she’s getting bigger. And we reminded her about it multiple times before the trip and on the way - by the time she got there she was super excited about the big bed. We were very clear she could not get down from the bed without our help. We used extra pillows to bulk up the foot and head of the bed, but if she’s on a pull out couch you may not need to do this. We bought these inflatable bumpers for the sides to keep her from rolling off. We had no trouble both with her falling asleep or staying in the bed.
[2-Pack] hiccapop Inflatable Bed Rail for Toddlers | Travel Bed Rail, Blow-up Bed Bumper with Soft, Non-Slip Machine-Washable Cover | Portable Bed Rail for Hotel, Grandma's, Vacation https://www.amazon.com/dp/B07GXX11ZV/ref=cm_sw_r_cp_api_glt_fabc_XM58PBV4XHB8TE5BYZBG?_encoding=UTF8&psc=1
She transitioned back to her crib without an issue at home. We’ve done this 3 times since February and each time she’s transitioned seamlessly from crib to bed to crib.
I use this one: [2-Pack] hiccapop Inflatable Bed Rail for Toddlers | Travel Bed Rail, Blow-up Bed Bumper for King, Queen, Full, with Non-Slip Machine-Washable Cover | Portable Bed Rail for Hotel, Grandma's, Vacation https://www.amazon.com/dp/B07GXX11ZV/ref=cm_sw_r_cp_api_i_A29ESR801P0TSKYK2M34
[2-Pack] hiccapop Inflatable Bed Rail for Toddlers | Travel Bed Rail, Blow-up Bed Bumper for King, Queen, Full, with Non-Slip Machine-Washable Cover | Portable Bed Rail for Hotel, Grandma's, Vacation https://www.amazon.com/dp/B07GXX11ZV/ref=cm_sw_r_cp_api_glt_fabc_DQPPN9V7XKKRHFDAZVSB?_encoding=UTF8&psc=1
I got inflatable bed rails when we traveled, I’ve also heard of people using pool noodles
Inflatable bed bumpers have been legit for ours. He’s 3 and we can keep him contained with these.
https://www.amazon.com/hiccapop-Inflatable-Toddlers-Water-Resistant-Removable/dp/B07GXX11ZV
We used the pnp for my daughter up until she was 32 months old and she's a big girl... we definitely used it past the weight & height limit, because we figured it would be safer than putting her in a bed she could fall/climb out of. But once she hit maybe 37 lbs, we bought these: https://www.amazon.com/hiccapop-Inflatable-Toddlers-Water-Resistant-Removable/dp/B07GXX11ZV?th=1 and they have worked great. She can climb over them, but we bring our monitor with us when we travel and just keep an eye on her til she falls asleep.
They have inflatable ones that go under the mattress pad! Great for travel. [2-Pack] hiccapop Inflatable Bed... https://www.amazon.com/dp/B07GXX11ZV?ref=ppx_pop_mob_ap_share