I visited Kathmandu earlier this year. I did not notice any transfer desks in the immigration arrival hall (more like a large room) and there didn't seem to be anywhere or anything to do in that room - you would be bored. Your best off entering Kathmandu even if for only a few hours but you won't have much time to do much from the point of passing through immigration (figure an hour from the time you actually deplane until you get your credentials approved at immigration) until it's time to enter the departure check-in lobby to get boarding passes (and you can only enter that lobby once the check-in counters open for your airline). Since lodging is so inexpensive, I suppose you get book a very low-cost room at a lodge to shower and relax; and then you will have a hotel to list on the VOA form, or you could just write "transit" for hotel and see what happens. The traffic near the airport is horrendous and one could almost walk as fast as cars can move down the road so make sure you book a place that is not more than 1/2 mile from the airport.