Bubble tip anemones aren't overly difficult in stable tanks. Most of the time, there's issues because people do not put them in established tanks or don't have proper lighting.
Some good substitutes are:
Torch coral
Frogspawn
Hammer coral
I've also seen clowns being hosted by yellow star polyps, candy cane coral, long tentacle and short tentacle plate corals, and clove polyps.
Keep in mind that a lot depends on the type of clown and how much damage they cause to a coral. Maroon clowns are very rough on their hosts, and will usually beat a coral host to death. My Ocellaris were hosted by candy cane coral and torch coral before they took to their BTA, but once they realized there was an anemone in the tank, they ignored the previous coral hosts. Luckily they didn't harm any of my corals.