I re did mine again last year after doing it for the first time a few years before that. The first time was a horrible dirty job getting all the muck up, second time was a breeze didn't take much to do it.
I got the bituman paint from the marina, wore old overalls, long marigold gloves taped up, shoe protectors and a shoe protector fitted over my hair (I've got short hair), and wore a proper breathing mask with filters in which helped with the smell.
I used a combination of brush and roller several coats leaving a few days between each coat and because we don't live on the boat I left it for a few weeks to cure.
Gave it a good rinse out before I re filled it again.
I will probably do it again in the next few years while its easy to do.