Smallest unit a mech can ride?

[SCC]

Hmm... and since the mech's ability to attend in the boat is not affected by said boat's shutdown status...

New question! What's the smallest ground unit that can legally carry a 300.5-ton boat? :D

Something with that much cargo space? I don't think there are really any rules for carrying Large Navel ships.

[Scotty]

Smallest? A single infantry trooper.

I think the implied requirement was "more than once".

[Iceweb]

I wanna stay out of any house rules here but maybe we are looking at it wrong on mobile structure. 

What if you just used a structure?  Make a building in one (or more) hexes shaped like a throne and all and have it move through the hex.  Since you mentioned Solaris not sure if you are using 30 sized hexes or 7 sized hexes (it is 7 right?) but 30 should be plenty to ride the throne and warm up the crowd. 
I'm not aware of any rules for conveyor belts in any books but they have to exist in the BTech universe.  Fluff a conveyor belt moving the throne part of the structure to other parts of this multi-hex building?  Since the building exists you can put an elevator on the bottom and rise up. 

Building rules are pretty open also, could be a transparent building, could just be the throne and fireworks and conveyor belts.  But if the building is made with a door for the Battlemech to exit through you wouldn't need a piloting roll to exit the building and starting in a building and leaving it are totally legal in the rules.  No cargo needed.

[Weirdo]

Remember, the idea was for rules-legal. By that I meant no house rules whatsoever.

Also:

Since you mentioned Solaris not sure if you are using 30 sized hexes or 7 sized hexes (it is 7 right?) but 30 should be plenty to ride the throne and warm up the crowd. 

...I have no idea what you're talking about here. A hex is a hex, given that we're talking about TW-scale mech combat.

[SCC]

I think he's taking about hex size in meters.

[idea weenie]

Hmm... and since the mech's ability to attend in the boat is not affected by said boat's shutdown status...

New question! What's the smallest ground unit that can legally carry a 300.5-ton boat? :D

An 80-ton Mech with four Lift Hoists?  This way the Mech carries the boat it is standing on

[Liam's Ghost]

...I have no idea what you're talking about here. A hex is a hex, given that we're talking about TW-scale mech combat.

Presumably he was talking about the old Solaris rules.

An 80-ton Mech with four Lift Hoists?  This way the Mech carries the boat it is standing on

Mechs can only carry a maximum of two lift hoists. Vehicles can carry up to four.  A 151 ton superheavy vehicle would seem to be the minimum required to lift 300.5 tons

[SCC]

Mechs can only carry a maximum of two lift hoists. Vehicles can carry up to four.  A 151 ton superheavy vehicle would seem to be the minimum required to lift 300.5 tons

I'd assume that capacity is round down and say you should have a 152 ton unit.

This also assume that a lot of other rules function in favor of this situation.

[Col Toda]

Rail Car would  be my guess

[Asgo]

...
New question! What's the smallest ground unit that can legally carry a 300.5-ton boat? :D

carry directly or carry a pool large enough a ship can legally swim in it? ;)

if we are going nesting doll :)

let's go straight to the root and ask if a turtle carrying a world is rules legal?