http://www.fishlakefalcon.com/Jim is Treeeeemendous. Heck of good person too. Electronics well I am sure he can show you how he uses his, but March is not a real big time off shore month to be honest.
http://www.robertsfishntackle.com/Great guy and good stick......not much on the electronics though.
Tgutie (posting handle here) He runs a Bass Cat and has HDS units AND 1100 series Hbirds that he runs at the same time. He is just starting out in the guiding business, but im sure he could put you on fish and show you some tricks with the fishfinders.
I may be able to help you out as well, depending on which days in March. My 08 Bullet has Lowrance electronics and my 2011 z521 has 1100 series Humminbirds.....I am picking up the ranger tomorrow and I am not familiar with Hbirds, but plan on getting familiar with em real soon....lol.
Regardless of who choose, start making those calls/messages now. It will be REAL tough booking anybody for this March, but people cancel everyday.
Gl out there!