As with any endurance sport the aerobic base is critical for the support it provides to the event specific training. For the VK, event specific will mean high intensity, hard uphill running/hiking. For the mountain runners I coach I like to use the gym based ME during the base period before beginning to add more conventional uphill intervals. That is why the Mike Foote Big Vert plan is laid out is laid out in that fashion.
Even though we do not have a VK plan you can use the Big Vert plan scaled down to the under 50km level. Those scaling instructions do not apply to races under a few hours.
You will still want to keep to the 80-90:20-10% balance of Low to High intensity training volume. If your are confident that your aerobic base is good you will be doing most of base training in Zone 1.
Your event may be an hour but that does not mean that your training volume can drop by the same proportion as the decrease in event duration. The volume difference between marathon and 1/2 marathon, 10km training is far less than the shorter length might indicate. Many top 800m runners (less than 2min) are still doing 60+miles/week because that base is vital to all endurance athletes.
All that being said is that the shorter the event the more important the high intensity race specific training is to improved performance. You will not race well in the VK without that HIT.
I hope this helps,