I live in San Francisco and surf during the winter but every spring the winds pick up and I'd like to get into kite landboarding. I have no experience and I'm child sized. 5'2" 100lbs. Was looking at the modded Hydra 3 or 3.5. Is that too much kite for a beginner? Open to recommendation and would consider buying used.

Check out the tutorials at www.coastalwindsports.com . There is tons of good information there and a section on selecting your 1st kite.

The modded Hydra will likely be too little kite.

i think everyone should fly fb/handles early in their kitting (i wanted to stay on the bar)
imo...you at 100# will move on a landboard w/ that hydra or a 2.5/3fb...either way
hydra will get you out on a longboard in the water so there is that...lot to be said about being able
to play in the water w/ your kites...i'd just be worried abt you destroying it before you getting good w/ it
buy a used 2/3 and the 3.5 hydra....pblm solved
welcome aboard

Welcome to the forum and the addiction:-)

^ +1 for what those guys said.

Here's somewhere else to start:
http://www.powerkiteforum.com/viewthread.php?tid=28759#pid27...

You're the same size as my son was when he started flying and it wasn't long before he was on his landboard.
He started with a HQ Rush Pro 300 (not significantly different from the Hydra other than the closed cells). He quickly (within weeks) moved to 4 lines with handles (instead of 3 with a bar) and never looked back. I'd suggest starting with a 3meter - 4-line - and keeping to lighter winds until you have the hang of it.

Here's a good deal:
http://www.powerkiteforum.com/viewthread.php?tid=29800

Of course, at some point you'll consider moving to a de-power kite and harness (someone else'll chime in with that soon enough) but you gotta get the basics down first.

Everybody needs a 3 meter kite. And a Helmet.