I single stage in a similiar fermenter. All I do is place the lid on, cover w/ a plastic bag. and then wrap a sting twice around the bucket and tie snug. It will maintain a "good" seal and keep positive pressure for 7-10 days easily. After that I cold crash, keg /purge w/ co2 and cold condition.
IMHO, for ales that mature reasonably quickly, this provides less exposure than opening fermenters for sampling. transfers to secondary, bottling etc.