I find this topic interesting, I was a Fish and Wildlife officer in another state and have since moved onto another similar law enforcement agency.  It seems that the definition of a day is what is at hand.  In my professional opinion the term "day" would be 24hrs from the start of the shrimping activity.  WishinIwasfishin says the law is pretty straight forward on the definition of a day, I was unable to locate that definition and would be interested in the location of said definition.  There is a definition of a "trip" which is from the time you leave the dock until you return, so that may hold some weight.  There was also the question of 5 gallons per person per boat.  It seems that section 1.b below says that only 5 gallons are allowed per vessel.  1.a states that 2 or more harvesters aboard the vessel are subject to the vessel possession limit, meaning 5 gallons. 
The question as to the legallity of the frame net is somewhat suprising.  It seems very clear as long as the opening does not exceed 16ft.  The law makes no reference to the device that holds the net open.  If it is collapsable should be irrelevant to the function of the net during harvest.  It should be relatively easy to recieve a judgement from FWC on the frame net.  The individual field officers do not make rulings or judgements they simply enforce the law/regulations/ruling. Since I am new to Florida's system it may be somewhat different but all you "should" have to do is submit a request for judgement and/or visit the Commisioners office and talk to the Commissioner or Head of Law Enforcement.  The head of Law enforcement is probably the way to go since his word is generally what is enforced in the field.   I would not force FWC to give you a citation simply to recieve a judgement.  If you have local district commissioners you should contact that person and let them make the contacts for you.  I do have some personal freinds in FWC and will contact them to ask what the best procedure is and possibly get some good contacts for questions.  From my previous state job the general help line or ASKFWC is not staffed by certified law enforcement officers just general clerks or staff with basic knowledge, so their answers my not be correct, especially on something that is new or different. 
Back to the 5 gallons question,  as a sportsman, we all deal with the question of morals, ethics, ect.  Personally, the 5 gallons is there to protect the natural resource that we all so love, if you go home and dump the 5 gallons and come back for more are you following what the law is intending to do "the spirit of the law" which is protect the resource and share the opportunity for harvest with others.
I am not an FWC officer or even know the Florida laws very well. Just my $.02

68B-31.007 Statewide Recreational Shrimping Restrictions.

Except for persons harvesting shrimp commercially as either a food shrimp producer or a live bait shrimp producer, each person harvesting shrimp in or on the waters of the state shall comply with the requirements specified in this rule.

(1) Bag Limit –

(a) No person shall harvest more than five gallons of shrimp, heads on, per day; provided, however, that two or more harvesters aboard a single vessel in or on the waters of the state shall be subject to the vessel possession limit specified in paragraph (b).

(b) The possession of more than five gallons of shrimp, heads on, aboard a vessel in or on the waters of the state or on any dock, pier, bridge, beach, or other fishing site adjacent to such waters, at any time is prohibited.

(c) All shrimp harvested pursuant to this rule shall be landed in a whole condition. The deheading of such shrimp before landing is prohibited.

(2) Allowable Gear – No person subject to the requirements of this rule shall use any type of gear to harvest shrimp other than those types of gear specified herein:

(a) Landing or dip net with an opening no larger than 96 inches around the perimeter.

(b) Cast net with a stretched length (the distance from the horn at the center of the net, with the net gathered and pulled taut, to the lead line) no greater than 14 feet.

(c) Push net.

(d) 1. Except as provided in subparagraph 2., one frame net with an opening no larger than 16 feet around the perimeter, if deployed from a vessel or from a structure other than an operational bridge or causeway or catwalk attached to such bridge or causeway.

2. Frame nets shall not be considered an allowable gear for persons harvesting shrimp pursuant to this rule in any waters of the Southeast Region in Dade County.