Advice on beachcat selection for rig test platform

I am interested in testing 4 to 6 different rigs to use on a short-handed, large, light cruising catamaran. One potential challenge for a couple cruising a large cat is the size and weight of the typical main. In my view, this is no problem as long as all works well, but it can be a real issue if there is a failure. Many people have suggested solutions for this: ketch, bi-plane, aft-mast, wing masts, junk rig, Balestron; all are possible. While each has its proponents, I have not seen any direct, data-driven comparisons. There is also a subjective aspect to the decision. For example, ease of use is somewhat in the eye of the beholder.

My plan is to buy two relatively inexpensive and identical beachcats. I will modify one so it can easily switch between the 4 to 6 rigs that I choose, e.g. extra chain plates, structure, line-handling systems. I will use the other as the base line, after adjusting it to account for the weights and moments added to the modified model to allow for the permanent extra materials used to allow for multiple rigs (not the added weights of each of the new rigs).

Then, of course, I plan to sail them against each other collecting actual and qualitative data on performance. I will decide which rig I like the best and then scale up to a larger catamaran. I recognize that there may be some scaling issues, but I think that they are surmountable.

My question: which beach catamaran should I select as my test platform?

Some important criteria to consider (in no particular order):

• 17 to 25 feet long: smaller saves $$ on the boats, rigs and sails; larger may be easier to work with and adapt (see the next point)
• Able to take the added weight and structure necessary to test a half-dozen very different rigs
• Fiberglass (not sure that it would be easy to stick things to a rotomolded poly hull, although I can see some ways to avoid the problem, so I wouldn't completely rule them out)
• Simple: highest performance is not the key, but getting the boats in and out of the water has to be relatively easy (I can leave them rigged and in the water for some period of time however)
• Sails well: I am going to spend a lot of time on them; they should be fun; I prefer wings for comfort
• Identical: formula classes do not work unless the boats are the exact same version from the same manufacturer
• Easily available: obviously, my focus is on the rigs, so extra expense in buying the hulls takes away from the budget for rigs and sails
• I am located in the Northeast part of the United States

It might be useful, though not essential, to have three cross-beams to more easily accommodate the modifications that I will be adding to the test boat.

Suggestions anyone?