Nam Cat Tien - recommended tour or private driver hire?

We would dearly love to go to the Cat Tien National Park and stay from one evening. I want to avoid going on a large tour waiting around for people to be on time for the pick up etc. Can anyone recommend an efficient tour agency or is this something that two confident travellers can do themselves - if so, how from HCMC? What are the accommodation options once in the park? And if we are able to get ourselves there is there an option to hire a trekking guide and trip on the night jeep independently from within the park?
Is the boat trip down the river worth it on the second day (we will have done some boating in the Mekong Delta probably) or would you suggest getting a vehicle pick up straight to our chosen beach resort in Phan Thiet? Any tips at all on this trip would be much appreciated. Thanks in advance.