What modifiers for Size categories? (homebrewed Gurps/d20 hybrid)

[GM.Casper]

I am working on a Gurps/d20 hybrid rules. Character sheet will be in Excel, automating all the number crunching. Now, I need ideas what to do with Size categories. What modifiers should they give?
Stealth and Move Silent- penalties for larger than Medium, bonuses for smaller. No problem here.
Defenses against ranged attacks- passive bonus if you are smaller and harder to hit.
Dodge- should the bonuses apply even when two Tiny creatures are fighting?
Melee attacks, melee defenses- ?

And what are your thoughts on Strength, Dexterity, Constitution and Damage Reduction for larger creatures?
My size categories at the moment are:
Tiny (0.5 m), Small (1m), Medium (2m), Large (3m), Huge (5m)...

[Ashtagon]

Since you are going for computer number crunching, you could geekout and just have the modifiers be a logarithmic function based off actual height, and drop size categories completely.

[lesser_minion]

Since you are going for computer number crunching, you could geekout and just have the modifiers be a logarithmic function based off actual height, and drop size categories completely.

Not everyone who plays a game is going to bring their laptop to the table while creating characters...

[Ashtagon]

Not everyone who plays a game is going to bring their laptop to the table while creating characters...

The OP specifically said they are. Or at least, strongly implied it by saying character sheets are in excel, as opposed to, say, in pen and paper.

[lesser_minion]

The OP specifically said they are. Or at least, strongly implied it by saying character sheets are in excel, as opposed to, say, in pen and paper.

Yes, I know, but there might be other people who'd like to play the game when it's done. It's worth bearing in mind.

[GM.Casper]

The idea is to use Excel during game. Have it track injuries, roll dice, etc. On single click it can roll your attack, add all the modifiers, roll damage for the weapon currently equipped (and it tracks encumbrance too).