Checking available packet size every time will be slow. Perhaps a better option (memory permitting) is to give yourself some extra room. To increase it just set it in your config:

[root@devel3 root]# cat /etc/my.cnf
[client]
socket=/tmp/mysql.sock

[mysqld]
datadir=/var/lib/mysql
socket=/tmp/mysql.sock
set-variable=wait_timeout=3600
set-variable=key_buffer=640M
set-variable=max_allowed_packet=32M
[snip]
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