Most BJJ players have very weak single legs on the mat. It is never going to threaten a decent wrestler. This is why I advocate defending a half guard player who has gotten too deep on you by purposely letting him come up on a single leg, defending against the back take and roll-over sweep (much harder to defend BJJ guys on these).
A weak single leg is not going to threaten anybody. Great players like Leite make up for this by their awesome knee torque single leg position on the mat. Without that torque, the bottom half guard player is rarely going to be able to threaten a good wrestler with a TD. Underhook half guard is like wrestling with the top guy, except your starting position is worse than a normal wrestler's position, more disadvantageous, plus you as a BJJ player don't know how to wrestle well either. Not likely to end up well.
Honestly you are probably better off playing a modern knee shield ... getting tight against a good wrestler is asking to get smashed.