How big is a base?

Dreaming about the Inuit HOTT army (given that it is 12C in my room) I’ve been looking through the piles of rules I have to see what else I can play and see if I can base the figures up to suit more than 1 set of rules.  Turns out this is a rather fruitless exercise as you will see…
First the rules:
Demon World – Forget it hex bases only…
HOTT – Plenty of troop types represented by generic types (e.g. Blades) with bases being key for recoil movement but not for troop definition.
AOMAS – Three classes of infantry split by ‘weight’ (e.g. Light / Medium / Heavy) defined by number of troops on the base.
MA – Bases are two standard sizes and play a key role in creating groups.
FR! – Standard bases but no real limit to the number of figures per base.
For example for basic foot troops:

Rules	Width	Depth	Figures
HOTT Blades	40mm	15mm	3 or 4
AOMAS	40mm	20mm	2-3-3
MA	50mm	25mm	4
FR!	40mm	40mm	Not defined

Characters add a whole new problem:

Rules	Width	Depth	Figures
HOTT Dragon	40mm	60mm	1
HOTT Magic	40mm	40mm	1
HOTT God	40mm	30mm	1
AOMAS	25mm	25mm	1
MA	50mm	50mm	1
FR!	40mm	40mm	Not defined

As the above shows – nice selection of sizes to play with but nothing in common with each other and in one case (AOMAS) the actual layout of figures on the base define the class of troops!
So how do I deal with this:

1. Stick to two sets of rules to start with – HOTT and MA
2. By basing on magnetic sheets I can use metal based sabot style bases for the larger requirements.  Have a look at my trees here
3. Characters are so rare / special I can have multiple one of the same figure for minimal cost as required
4. HOTT has the smallest base size so that becomes the standard

Sorted!