That's going to be one beautiful tank! It looks much bigger than 60 gallons.
I currently have 3 tanks with soil sub. What I like about them is I don't have to dose. I've been extremely busy this summer and really haven't touched them. 2 look great. One has green spot Big time. I think it needs a new bulb though. Now, in the winter when I'm bored, I do sometimes test, dose and trim things up a bit. The flexablity is what I like most about soil. The plants and fish I see would make good canidates for a soil tank. I don't know a way to add soil to what you have already set up without making a huge mess of it.
I don't know that I'd recommend it, but I've left my tanks for up to ten days. I heavily feed fish for a week before. Drop the temps about 2-4 degrees. Shut off the lights while I'm gone. And darken the room. Put everything in a coma. When I come home I find that I have an algae free tank. Leaner, hungry fish. And the plants are alive and take right off again after a long rest. But I give no guarentees.
But when you get back from vacation, think about ditching the biowheel.
Good luck and enjoy your vacation.