They need to be on a round base. A design like that, even if it is the same overall area, can zoom through blastmarker and whatnot much easier.
When I get my BFG back (still in House Hold Goods shipment coming back from Japan) I am going to be using nuts and bolts to mount them. Basically intend to attach a small nut to the bottom of each ship and a bolt to the base. THen I just screw on the ships for games and unscrew them for storage. Likely going to drill up into the ship still some so it isn't just the tip of the bolt in the nut.
I also kinda want to do a display diorama, so I can put the bolts in all over the place and at multiple angles to get cool effects.