You need to drill holes in the floor yes.
They are easy to fit, I don't have any pics of them fitted but do have an article from Camper & Bus showing how to fit...
Imported from Oregon in 2014
Re-con Steve Strong engine 5k miles ago - 1600 TP
Alternator conversion
New battery
New rear shocks
New front air shocks
MOT Feb 2018
In Wigan