Just a note, you ask about a 222 traveler, but your profile says you have an O'day 22. 2 different boats...
That being said, there are probably 2 options for putting a traveler an O'day 222. One option is to change it to mid-boom sheeting, and build a raised traveler bridge somewhere across the seats aft of the bridge deck. Putting a traveler on the bridge deck itself might not offer enough travel to center the boom, or to dump for a puff. Here is a picture of Joe Alvez's raised teak traveler bridge on his 222 Trinkka:
My second thought is to keep the end boom sheeting, and to install a raised traveler assembly on the aft coaming. This would be desirable because the boom tubing section is used keeping end boom sheeting in mind, rather than the different stresses of mid boom sheeting. That being said, Joe sailed his for many years without trouble. Also, keeping end boom sheeting allows for more space in the cockpit. Given that the 222 was designed as a cruising boat, end boom sheeting was likely selected to allow for the greatest cockpit area. The drawback to this plan is that the traveler bridge has to be tall enough to allow for tiller clearance, and this would make it more difficult to climb over using the swim ladder. I for one swim off the boat frequently...