Asia Shore Excursions for senior using 2 walking sticks

[SF2LV]

My 72 year old husband has mobility issues and uses 2 sticks to walk.  He can maneuver on his own fairly well but needs handrails when using stairs and moves slowly when walking especially over uneven surfaces. How difficult would it be for him on a Celebrity Cruise from Hong Kong to Singapore? We will be doing pre cruise touring of Hong Kong on our own and then stopping in Chan May, Ho Chi Minh City, Amphoe Ko Samui, with overnights in Hanoi and Bangkok. We would specifically like to do the overnight bus ride and hotel stay in Bangkok but it states that it is strenuous and it doesn’t recommend that someone with mobility issues take it.  We would also like to take a boat cruise along Halong Bay.  How difficult would it be to get on and off the those boats? Would it be as difficult as getting on a gondola in Venice?